New optional ZONE arg for format-time-string etc.

New optional ZONE arg for format-time-string etc.

This simplifies time conversions in other time zones.
It also prevents display-time-world tampering with TZ (Bug#21020).
* admin/admin.el (add-release-logs):
Use improved add-log-time-format API.
* admin/merge-gnulib (GNULIB_MODULES): Add time_rz, timegm.
(GNULIB_TOOL_FLAGS): Avoid flexmember, setenv, unsetenv.
* configure.ac (tzalloc): Remove test for this, since
Emacs no longer uses HAVE_TZALLOC directly.
* doc/lispref/os.texi (Time of Day, Time Conversion)
(Time Parsing):
* etc/NEWS: Document the new behavior.
Merge from gnulib, incorporating:
2015-07-25 strftime: fix newly-introduced bug on Solaris
2015-07-23 fprintftime, strftime: use timezone_t args
* lib/gnulib.mk, m4/gnulib-comp.m4: Regenerate.
* lib/strftime.c, lib/strftime.h, lib/time.in.h, m4/sys_time_h.m4:
* m4/time_h.m4:
Update from gnulib.
* lib/time_rz.c, lib/timegm.c, m4/time_rz.m4, m4/timegm.m4:
New files from gnulib.
* lisp/time-stamp.el (time-stamp-string):
* lisp/time.el (display-time-world-list)
(display-time-world-display):
Use new API, with time zone arg.
* lisp/time.el (display-time-world-display):
Fix race when current-time advances while we're running.
* lisp/vc/add-log.el (add-log-iso8601-time-zone)
(add-log-iso8601-time-string): Accept optional time zone arg.
* lisp/vc/add-log.el (add-change-log-entry):
* lisp/vc/log-edit.el (log-edit-changelog-ours-p): Use new arg.
* nt/gnulib.mk: Propagate lib/gnulib.mk changes here.
Add rules for the time module, since they're now needed
for tzalloc etc.
* src/conf_post.h (getenv_TZ, setenv_TZ): New macros.
(emacs_getenv_TZ, emacs_setenv_TZ): New decls.
* src/editfns.c: Include errno.h.
(set_time_zone_rule): Omit unnecessary forward decl.
(initial_tz): Remove, replacing with ...
(local_tz, wall_clock_tz, utc_tz): New static vars and constants.
(tzeqlen): New constant; prefer it to (sizeof "TZ=" - 1).
(emacs_localtime_rz, emacs_mktime_z, xtzalloc, xtzfree)
(tzlookup): New static functions.
(init_editfns): New arg DUMPING.  All uses changed.
(init_editfns): Omit most initialization if dumping, not if
!initialized.  Initialize wall_clock_tz and local_tz.
(emacs_nmemftime, format_time_string): Time zone argument can now
be any time zone, not just a boolean for UTC or local time.  All
callers changed.
(Fformat_time_string, Fencode_time, Fcurrent_time_string)
(Fcurrent_time_zone): New optional arg ZONE.
(Fdecode_time, Fset_time_zone_rule): ZONE arg can now also take
the same form as with the other new additions.
(decode_time_zone): Remove; no longer needed.
(tzvalbuf): Now file-scope.
(emacs_getenv_TZ, emacs_setenv_TZ): New functions.
(syms_of_editfns): Define Qwall.
* src/editfns.c (mktime_z) [!HAVE_TZALLOC]:
* src/systime.h (mktime_z, timezone_t, tzalloc, tzfree)
[!HAVE_TZALLOC]:
Remove; now supplied by gnulib.
* src/emacs.c (main):
* src/lisp.h (init_editfns): Adjust to init_editfns API change.