image-dired: Prefer command remapping

* lisp/image/image-dired.el (image-dired-thumbnail-mode-map):
Prefer command remapping to binding keys directly.

image-dired: Fix C-a/C-e in thumbnail buffer

* lisp/image/image-dired.el
(image-dired--movement-ensure-point-pos): New function, and...
(image-dired--movement-command): ...new macros broken out from...
(image-dired-next-line, image-dired-previous-line)
(image-dired-beginning-of-buffer, image-dired-end-of-buffer):
...here.
(image-dired-move-beginning-of-line)
(image-dired-move-end-of-line): New commands.
(image-dired-thumbnail-mode-map): Remap 'move-beginning-of-line'
and 'move-beginning-of-line' to above new commands.

Make thumbs.el obsolete

* lisp/obsolete/thumbs.el: Add Obsolete-since.
* etc/NEWS: Announce obsoletion of thumbs.el.  (Bug#57779)

Move thumbs.el to lisp/obsolete

* lisp/thumbs.el:
* test/lisp/thumbs-tests.el: Move from here...
* lisp/obsolete/thumbs.el:
* test/lisp/obsolete/thumbs-tests.el: ...to here.  (Bug#57779)

image-dired: Regenerate old thumbnails when needed

* lisp/image/image-dired.el
(image-dired--get-create-thumbnail-file): Rename from
'image-dired-get-thumbnail-image'.  Update callers and make old
name into an obsolete alias.
(image-dired-display-thumbs): Use above function to simplify and
regenerate the thumbnail if it's outdated.

image-dired: Improve performance of marking commands

* lisp/image/image-dired.el (image-dired-thumbnail-storage): Mark
(image-dired--thumb-update-mark-at-point): New function.
(image-dired--thumb-update-marks):
(image-dired--do-mark-command):  Use it.
(image-dired--thumb-update-marks): Rename from
'image-dired-thumb-update-marks'.  Update all callers and make the
old name into an obsolete alias.

image-dired: Mark 'per-directory' as :safe

* lisp/image/image-dired.el (image-dired-thumbnail-storage): Mark
'per-directory' value as :safe.

Add new macro image-dired--with-dired-buffer

* lisp/image/image-dired-util.el
(image-dired--with-dired-buffer): New macro.
* lisp/image/image-dired.el (image-dired-track-original-file)
(image-dired--on-file-in-dired-buffer)
(image-dired--do-mark-command)
(image-dired--on-file-in-dired-buffer)
(image-dired-jump-original-dired-buffer)
(image-dired-thumb-file-marked-p, image-dired-delete-marked):
Use above new macro to simplify and improve error handling.
(image-dired-show-all-from-dir): Simplify removing Dired marks.
(image-dired-thumb-update-marks): Avoid triggering above new error
handling.

Tweak how :override advice is formatted in *Help*

* lisp/emacs-lisp/nadvice.el (advice--make-single-doc): Format
:overrides specially (bug#57974).
(advice--make-docstring): Put overrides at the front.

Rename file-name-directory

* lisp/emacs-lisp/shortdoc.el (file-name):
* doc/lispref/files.texi (Directory Names): Adjust.
* lisp/files.el (file-name-parent-directory): Rename from
`file-name-directory' (bug#58039).

Ensure that cus-load doesn't add things twice

* lisp/cus-dep.el (custom-make-dependencies): Use it.

* lisp/custom.el (custom--add-custom-loads): New function.

`append' doc string clarification

* src/fns.c (Fappend): Clarify whether arguments are copied.

Clarify message-newline-and-reformat doc string

* lisp/gnus/message.el (message-newline-and-reformat): Clarify the
DWIM-ness in the doc string (bug#57986).

; * lisp/image/image-dired.el: Improve sectioning.

; Make 'M-x image-dired' prompt even clearer

* lisp/image/image-dired.el (image-dired-show-all-from-dir):
Make prompt even clearer.
Suggested by Eli Zaretskii <eliz@gnu.org>.

Improve image-dired-thumbnail-display-external

* lisp/image/image-dired.el: (image-dired-external-viewer): Add more
image viewers and slightly re-arrange.
(image-dired-thumbnail-display-external): Correctly handle
external viewers with spaces or flags.

* lisp/emacs-lisp/shortdoc.el (file-name): Improve examples.

image-dired: Use command substitution for tags bindings

* lisp/image/image-dired-tags.el
(image-dired-dired-edit-comment-and-tags): Use substitute-command-keys

image-dired: Various code clean ups

* lisp/image/image-dired.el
(image-dired--display-thumb-properties-fun): Delete function.
(image-dired-forward-image): Immediately update header line.  Improve
docstring.
(image-dired-backward-image, image-dired-next-line)
(image-dired-previous-line, image-dired-beginning-of-buffer)
(image-dired-end-of-buffer, image-dired-display-image): Improve
docstring.
(image-dired-comment-thumbnail): Fix interactive declaration.

Reduce complexity of scroll bar window protection code

It turns out my previous theories of why ClientMessages were
generated were wrong, and they are just generated so we can set
finish to X_EVENT_GOTO_OUT to have them delivered immediately.

This allows for the code to be simplified greatly, by not
unpacking pointers to the raw window into the client messages.

* src/xterm.c (x_unprotect_window_for_callback): Return the
window removed from the queue, or nil if none.
(x_scroll_bar_to_input_event)
(x_horizontal_scroll_bar_to_input_event): Use window provided by
x_unprotect_window_for_callback.
(handle_one_xevent): Pass dpyinfo to functions that need it.
(x_free_frame_resources): Remove "first scroll bar request"
code.

* src/xterm.h (struct x_display_info): Likewise.

New Flymake backend using the shellcheck program

See bug#57884.

* lisp/progmodes/sh-script.el: Require let-alist and subr-x when
compiling.
(sh--json-read): Helper function to deal with possible absence of
json-parse-buffer.
(sh-shellcheck-program, sh--shellcheck-process,
sh-shellcheck-flymake): Variables and function defining a Flymake
backend.
(sh-mode): Add it to 'flymake-diagnostic-functions'.

vc-git--pushpull: Restore handling of vc-git-program

* lisp/vc/vc-git.el (vc-git--pushpull): Restore handling of
vc-git-program before recent change: respect a buffer-local value of
vc-git-program, and don't ignore user edits to the git program name
when PROMPT.

* lisp/emacs-lisp/eieio.el (defclass): Fix bug#51068

Accept (defclass <class> <superclasses> (.. <slotname> ..)) without
having to wrap the slot name within parentheses.

image-dired: Rewrite and extend slideshow feature

* lisp/image/image-dired.el
(image-dired--slideshow-start-timer)
(image-dired--slideshow-stop-timer)
(image-dired--slideshow-show-message): New functions.
(image-dired--slideshow-current-delay): New variable.
(image-dired--slideshow-initial): Delete variable.
(image-dired-slideshow-start): Simplify and ensure we display the
image at start.
* lisp/image/image-dired.el (image-dired--slideshow-stop): Add support
for pausing, and going backwards and forwards during slideshow.

image-dired: Mark two slideshow defuns as internal

* lisp/image/image-dired.el (image-dired--slideshow-step)
(image-dired--slideshow-stop): Rename from
'image-dired--slideshow-step' and 'image-dired--slideshow-stop'.
Update callers and make old names into obsolete aliases.

cconv.el: Fix interactive closure bug#51695

Make cconv.el detect when a closure's interactive form needs to
capture variables from the context and tweak the code accordingly
if so.

* lisp/emacs-lisp/cconv.el (cconv--interactive-form-funs): New var.
(cconv-convert): Handle the case where the interactive form captures
vars from the surrounding context.  Remove left over handling of
`declare` which was already removed from the cconv-analyze` phase.
(cconv-analyze-form): Adjust analysis of interactive forms accordingly.

* lisp/emacs-lisp/oclosure.el (cconv--interactive-helper): New type and
function.
* lisp/simple.el (function-documentation, oclosure-interactive-form):
Add methods for it.

* test/lisp/emacs-lisp/cconv-tests.el
(cconv-tests-interactive-closure-bug51695): New test.

Make Gnus respect mode-line-buffer-identification-keymap

* lisp/gnus/gnus-group.el (gnus-group-set-mode-line): Use
'propertized-buffer-identification' to buttonise and fontify the
buffer name.
* lisp/gnus/gnus-sum.el (gnus-set-mode-line):
* lisp/gnus/gnus.el (gnus-mode-line-buffer-identification): Adjust
calls to above.
* lisp/gnus/gnus-srvr.el (gnus-browse-foreign-server): Add missing
'gnus-modeline-buffer-identification' call (bug#57977).

Make bounding box of 'image-crop' more noticeable

* lisp/image/image-crop.el (image-crop--crop-image-1): Darken the
selected region to make the bounding-box more noticable in images
which are mostly white (bug#58004).

Don't overwrite cus-load dependencies

* lisp/cus-dep.el (custom-make-dependencies): Don't overwrite
elements added by packages (bug#58015).

Make loaddefs-gen register parent :groups from defcustom

* lisp/emacs-lisp/loaddefs-gen.el
(loaddefs-generate--make-autoload): Also register parent :groups from
`defgroup' entries (bug#58015).

Fix syntax check in python-info-looking-at-beginning-of-defun

* lisp/progmodes/python.el
(python-info-looking-at-beginning-of-defun): Check syntax after moving
to the beginning of line.
* test/lisp/progmodes/python-tests.el (python-nav-beginning-of-defun-6)
(python-end-of-defun-1, python-info-looking-at-beginning-of-defun-3):
New tests (bug#58023).

Inhibit image-crop when there's overlays

* lisp/image/image-crop.el (image-crop): Don't mess with overlays,
because they're a pain to reconstruct (bug#58027).

Delete the correct region after cropping an image

* lisp/image/image-crop.el (image-crop): Delete the correct region
after editing (bug#58027).

image-dired: Disable 'image-map' in thumbnail buffer

These bindings are more likely to mess up the buffer than to be
helpful here; image manipulation is better done in the display buffer.

* lisp/image/image-dired.el (image-dired-insert-thumbnail): Disable
`image-map' in thumbnail buffer.

Update manual for recent image-dired changes

* doc/emacs/dired.texi (Image-Dired): Update to reflect recent
changes.

* lisp/files.el (risky-local-variable): Remove max-specpdl-size.

Remove max-specpdl-size overrun test

* test/src/eval-tests.el (eval-tests--exceed-specbind-limit)
(eval-exceed-specbind-with-signal-hook): Remove test that is
no longer useful, since there is no longer any specpdl limit
to overrun.  (The test still passed but vacuously so, by
hitting the max-lisp-eval-depth limit instead.)
This silences an obsoletion warning.

; Fix :type of image-dired-thumbnail-storage

* lisp/image/image-dired.el (image-dired-thumbnail-storage): Fix
:type for recent change.

* lisp/bookmark.el (bookmark-make-record): Fix thinko.

; Fix warnings in --without-x build

* lisp/image/image-crop.el (image-scaling-factor)
(image-property, image-size, imagep):
* test/src/image-tests.el (image-size, image-mask-p)
(image-metadata): Declare.

Improve prompt of 'image-dired' command

* lisp/image/image-dired.el (image-dired-show-all-from-dir):
Improve prompt.

Rename 'image-dired-db-file' to 'image-dired-tags-db-file'

* lisp/image/image-dired.el (image-dired-tags-db-file): Rename
from 'image-dired-db-file'.  Update all uses and make old name
into an obsolete variable alias.

Merge from origin/emacs-28

60ac12d21f Fix shaping with bitmap-only fonts on HarfBuzz 5.2.0 (Bug#...
9f65e52362 ; Minor copyedits of elisp.texi

Fix more toolkit scroll bar window protection issues

* src/xterm.c (handle_one_xevent): Ignore outdated scroll bar
events.
(x_free_frame_resources): Clear protected windows and invalidate
previous scroll bar events.
* src/xterm.h (struct x_display_info): New field
`first_valid_scroll_bar_req'.

Autoload wallpaper-set

* lisp/image/wallpaper.el (wallpaper-set): Autoload.
* lisp/image-mode.el (wallpaper):
* lisp/image/image-dired.el (wallpaper):
* lisp/thumbs.el (wallpaper): Don't require.

Support Noto Emoji font as fallback

The black-and-white emoji font is back under active development,
see https://github.com/googlefonts/noto-emoji.  So this adds
that font as fallback for systems that don't have the capability
of using color fonts.
* lisp/international/fontset.el (setup-default-fontset): Support
black-and-white Noto Emoji font as fallback for Emoji display.

Fix shaping with bitmap-only fonts on HarfBuzz 5.2.0 (Bug#57976)

* src/ftcrfont.c (ftcrhbfont_begin_hb_font): Undo last change for
HarfBuzz 5.2.0.

; * lisp/image/wallpaper.el: Fix last commit.

Support several new DEs in wallpaper.el

* lisp/image/wallpaper.el (wallpaper--default-commands)
(wallpaper--check-command, wallpaper-command): Add support for Unity,
Pantheon, Budgie, LXQt, and LXDE.  Also add support for Lubuntu,
Xubuntu, and Pop!_OS.

image-dired: Obsolete two unused functions

* lisp/image/image-dired-util.el (image-dired-display-window)
(image-dired-associated-dired-buffer-window): Make obsolete; they are
currently unused.

; * Makefile.in: Make install depend on actual-all. Fixes bug#57959.

; Minor copyedits of elisp.texi

* doc/lispref/variables.texi (Setting Generalized Variables):
Improve wording.

Don't rewrite `set` to `setq` of lexical variables

Only perform the rewrite

   (set 'VAR X) -> (setq VAR X)

for dynamic variables, as `set` isn't supposed to affect
lexical vars (and never does so when interpreted).

* lisp/emacs-lisp/byte-opt.el (byte-optimize-set):
* test/lisp/emacs-lisp/bytecomp-tests.el (bytecomp-tests--xx): New.
(bytecomp-tests--test-cases): Add test cases.
* test/lisp/emacs-lisp/bytecomp-resources/warn-variable-set-nonvariable.el:
Remove obsolete test.

image-dired: Improve minor mode docstring

* lisp/image/image-dired-dired.el (image-dired-minor-mode):
Improve docstring.

image-dired: Remove redundant keybindings

* lisp/image/image-dired-dired.el (image-dired-minor-mode-map):
Don't redundantly bind keys that are already bound in dired.

Fix failing image-dired test

* test/lisp/image/image-dired-util-tests.el (ert-x, xdg): Require.
(image-dired-thumb-name/): Delete test.
(image-dired-thumb-name/standard)
(image-dired-thumb-name/image-dired)
(image-dired-thumb-name/per-directory): New tests.

Add X-Hashcash to the end of mail headers

* lisp/mail/hashcash.el (mail-add-payment): Move headers to the end of
the headers.

; * lisp/mail/hashcash.el: Remove redundant :group args.

Improve don't save bookmark context from encrypted files

* etc/NEWS: Mention 'bookmark-inhibit-context-functions'.
Fix typos.

* lisp/bookmark.el (bookmark-inhibit-context-functions): New defcustom.
(bookmark-make-record): Use it.

* lisp/auth-source-pass.el (auth-source-pass-file-name-p):
* lisp/auth-source.el (auth-source-file-name-p): New defuns.  Add
them to `bookmark-inhibit-context-functions'.

* lisp/epa-hook.el (epa-file-name-p):
* lisp/net/tramp-crypt.el (tramp-crypt-file-name-p): Add them to
`bookmark-inhibit-context-functions'.

Work around rare crash when turning scroll wheel

* src/xterm.c (handle_one_xevent): Don't allow devices to be
added twice handling hierarcy events.

Add support for user edits to VC command arguments

* lisp/vc/vc-dispatcher.el (vc-pre-command-functions): New hook.
(vc-want-edit-command-p): New variable.
(vc-do-command): If vc-want-edit-command-p is non-nil, prompt the user
to edit the VC command & arguments before execution.  Run the new hook.
(vc-do-async-command): Use the new hook to insert into BUFFER the
command that's next to be run.
* lisp/vc/vc-git.el (vc-git--pushpull): Drop prompting code.  Bind
vc-want-edit-command-p so that vc-do-command handles the prompting.
Use the new hook to update compile-command with the edited command.
* lisp/vc/vc.el (vc-print-branch-log): A non-nil prefix argument now
means vc-want-edit-command-p is bound to a non-nil value (bug#57807).

Prefer command remapping in image-dired-minor-mode

* lisp/image/image-dired-dired.el (image-dired-minor-mode-map):
Prefer command remapping.
(image-dired-minor-mode): Improve docstring.

Obsolete image-mode--images-in-directory

* lisp/image-mode.el (image-mode--images-in-directory): Make
unused function obsolete.

Update version tag of rmail-retry-ignored-headers

* lisp/mail/rmail.el (rmail-retry-ignored-headers): Set :version to "29.1".

; * lisp/emacs-lisp/gv.el (gv-synthetic-place): Doc fix.

* test/lisp/image/image-dired-util-tests.el: New file.

Add more headers to default value of rmail-retry-ignored-headers.

* rmail.el (rmail-retry-ignored-headers): Add more headers to default.
Don't bother with `purecopy'.  Split value readably.

; Explicitly declare linum-mode obsolete

* lisp/obsolete/linum.el (linum-mode, global-linum-mode):
Explicitly declare obsolete to warn the user, and recommend using
'display-line-numbers-mode' instead.
Suggested by Philip Kaludercic <philipk@posteo.net>.

Add new function xdg-session-type to xdg.el

* lisp/xdg.el (xdg-session-type): New function.

Correct the usage of `image-file-name-regexps'

* lisp/image-file.el (image-file-name-regexp): Treat
`image-file-name-regexps' as a list of regexps (as documented) in
addition to a regexp string (bug#57971).

Copyright-paperwork-exempt: yes

Fix handling of nil device names

* lisp/frame.el (device-class):
* lisp/term/pgtk-win.el (pgtk-device-class):
* lisp/term/x-win.el (x-device-class): Handle `nil'
correctly.  (bug#57969)

Small adjustments to precision pixel scrolling

* lisp/pixel-scroll.el
(pixel-scroll-precision-interpolation-factor): Adjust for
increased accuracy.
(pixel-scroll-precision-interpolate): Slightly decrease accuracy
in exchange for consing less floats.
(pixel-scroll-interpolate-down, pixel-scroll-interpolate-up):
Fix usage of function.

Improve scroll interpolation in pixel-s-precision-mode

* lisp/pixel-scroll.el (pixel-scroll-precision-interpolate): New
arg FACTOR.  Use it to determine the interpolation factor if
non-nil.  Also, clear scroll remainder if direction changes, and
determine deltas based on the absolute amount of time passed.
(bug#57967)
(pixel-scroll-interpolate-down, pixel-scroll-interpolate-up):
Pass factor of 0 to scroll exactly 1 page.

Make emacs-build-description into a command

* lisp/mail/emacsbug.el (report-emacs-bug, submit-emacs-patch):
Adjust callers.
(emacs-build-description): Rename from
`emacs-bug--system-description' and make into a command.

; * Makefile.in: Minor improvements of failure messages.

Merge from origin/emacs-28

478b786d5a ; * doc/lispref/windows.texi (Window Hooks): Fix a typo (b...
5085351645 * lisp/text-modes/tex-mode.el (tex-mode): Fix AUCTeX regre...
ee6f8598ca Add vc-annotate-switches to manual
616dcf27e5 ; Fix typos in Lisp symbols
5405852541 Remove mention of non-existent `annotate-switches'
191505b8a3 Mention that src/macuvs.h sometimes needs committing
10373c4b68 ; More comment fixes in font.h (bug#57935)
c2595b8dcc ; * src/font.h (struct font_driver): Comment fix.
97b928ce09 MacOS ld warning from native compilation (bug#57849)

* admin/gitmerge.el (gitmerge): Use substitute-command-keys.

Bind 'n'/'p' in gitmerge-mode to line scroll

* admin/gitmerge.el (gitmerge-mode-map): Bind 'n' and 'p' to
'next-line' and 'previous-line'.

Fix substitute-command-keys for global binding lookup

The previous change forgot to account for the (rare) case of doing a
lookup for a global binding when a specific keymap is in force.

* lisp/help.el (substitute-command-keys): Redo lookup in global map if
lookup in specific map fails.
*
test/lisp/help-tests.el (help-tests-substitute-command-keys/keymap-change):
Add testcase for specific map overriding advertised-binding.

* lisp/outline.el: More improvements for buttons/margins (bug#57813)

(outline-minor-mode-use-margins): Don't use for modes derived from help-mode
that are handled by 'outline-minor-mode-use-buttons'.
(outline-open, outline-close, outline-close-rtl): Use image height
proportional to font height of 0.8em.
(outline-minor-mode): Remove overlays 'outline-button' and 'outline-margin',
and move such overlay removal after the call of 'outline-show-all'
that might trigger overlay addition.

image-dired: Support the customize-mode command

* lisp/image/image-dired.el (image-dired-thumbnail-mode)
(image-dired-display-image-mode): Add custom group 'image-dired'.

Fix minor thinko in focus tracking logic

* src/xterm.c (xi_handle_focus_change): Prefer explicit focus to
implicit focus.

Recognize the backslash operator in perl-mode

* lisp/progmodes/perl-mode.el (perl-syntax-propertize-function):
Add new rule to detect a backslash operator.  (Bug#11996)

* test/lisp/progmodes/cperl-mode-tests.el (cperl-test-bug-11996): New
test.

* test/lisp/progmodes/cperl-mode-resources/cperl-bug-11996.pl: New
file.

Make linum.el obsolete

* lisp/obsolete/linum.el: Add Obsolete-since.
* etc/NEWS: Announce obsoletion of linum.el.  (Bug#57412)

* doc/misc/efaq.texi (Displaying the current line or column):
* etc/TODO:
* lisp/faces.el: Don't mention linum.el.

Move linum.el to lisp/obsolete

* lisp/linum.el: Move from here...
* lisp/obsolete/linum.el: ...to here.  (Bug#57412)

; * doc/misc/gnus-faq.texi: Repunctuate sentences.

* doc/misc/ede.texi (Extending EDE): Fix reference.

; * doc/lispref/windows.texi (Window Hooks): Fix a typo (bug#51930).

; * doc/misc/rcirc.texi: Prefer 'setopt' over 'setq'

; * doc/misc/rcirc.texi: Repunctuate some sentences

; Don't set nil to be a face fore-/background

* lisp/net/rcirc.el (rcirc-color-attributes): Check if the parsed
background or foreground is nil before using it.

Have rcirc handle bridge bots

* doc/misc/rcirc.texi (Dealing with Bridge Bots): Document new feature.
* etc/NEWS: Mention the new feature.
* lisp/net/rcirc.el (rcirc-markup-text-functions): Add new markup function
(rcirc-pseudo-nicks): Add new local variable.
(rcirc-channel-nicks): Use 'rcirc-pseudo-nicks' for nick completion.
(rcirc-bridge-bot-alist): Add new user option.
(rcirc-bridged-nick): Add new face.
(rcirc-markup-bridge-bots): Add new function.

Merge branch 'master' of git.sv.gnu.org:/srv/git/emacs

; Minor Tramp cleanups

* lisp/net/tramp.el (tramp-build-remote-file-name-spec-regexp):
Handle the `simplified' syntax better.
(tramp-handle-file-name-case-insensitive-p): Do not unquote candidate.

* lisp/outline.el: Bind margin mouse event to cycle outlines (bug#57813)

(outline-minor-mode): In mode keymap bind
'right/left-margin mouse-1' to outline-cycle, and
'right/left-margin S-mouse-1' to outline-cycle-buffer.
(outline-hide-subtree, outline-show-subtree): Add save-excursion
to keep point unmoved after mouse click.
(outline-cycle): Add optional arg 'event' like in
outline-hide-subtree and outline-show-subtree, and
add save-excursion to keep point unmoved after mouse click.
(outline--make-button-overlay, outline--make-margin-overlay):
Put overlay property 'evaporate' to t.
(outline--insert-open-button, outline--insert-close-button):
Remove temporary attempts to bind margin-local mouse events.

Allow keymap to override advertised-binding in docstrings

Previously

(substitute-command-keys "\\<undo-repeat-map>\\[undo]")

would use the global advertised-binding for `undo', even though
there's a binding in `undo-repeat-map', which is highly
counter-intuitive.  Now the binding is looked up in the specified
keymap first.

* lisp/help.el (substitute-command-keys): Restrict the initial key
lookup to the specified keymap (if there is one).  (Bug#51384)

Specify keymap in gnus-custom-mode docstring

* lisp/gnus/gnus-cus.el (gnus-custom-mode): Put in the keymap to use,
otherwise the bindings are looked up in the global map (where they
don't exist).

Tweak how use-region-p works with `use-empty-active-region'

* lisp/simple.el (use-region-p): Don't report non-nil if the user
has just clicked mouse-1 without extending the region (bug#51874).

Attempt to clarify Input Focus documentation

* doc/lispref/frames.texi (Input Focus): Try to clarify the
documentation (bug#51862).

Improve display of advices on build failures.

* Makefile.in: Use three leading '*' characters, and redirect to stderr.