Address some --without-x byte-compilation warnings

Address some --without-x byte-compilation warnings

These came to light in the contexts of bug#29713 and bug#47234.

* lisp/emulation/edt-mapper.el (edt-xserver):
* lisp/emulation/edt.el (edt-xserver):
* lisp/gnus/gnus-util.el (gnus-rescale-image):
* lisp/gnus/nnimap.el (nnimap-map-port):
* lisp/term/w32-win.el:
* lisp/image.el (image--get-imagemagick-and-warn):
* lisp/frame.el (frame-notice-user-settings): Declare functions that
are known to be present at runtime in GUI builds.
(make-frame-on-display): Signal more informative error when called
interactively in a non-GUI build (bug#29713).
* lisp/international/mule-diag.el (describe-font):
* lisp/org/org-macs.el (org--string-from-props): Pacify warnings
about unknown functions in non-GUI bilds.
* lisp/mh-e/mh-mime.el (mh-small-image-p): Avoid eliminating fboundp
check in non-GUI builds, to pacify unused lexical variable warning.
* lisp/net/newst-plainview.el (newsticker--plainview-tool-bar-map):
* lisp/net/newst-treeview.el (newsticker-treeview-tool-bar-map):
Declare tool-bar-map as a special variable in non-GUI builds.