Add terminal hook defined_color_hook

* src/termhooks.h (defined_color_hook): New terminal hook.

* src/xterm.c:
* src/nsterm.m:
* src/term.c:
* src/w32term.c: Set defined_color_hook.

* src/nsterm.m (ns_defined_color_hook): New hook wrapper procedure.

* src/xfaces.c: Use defined_color_hook.
(defined_color): Remove.

* src/image.c (image_defined_color): New wrapper procedure for NS.
Remove redefinitions of x_defined_color, and rename x_defined_color to
image_defined_color.
2 jobs for scratch/x_emacs in 5 minutes and 15 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Test
failed #1338
test-all

00:04:50

failed #1339
test-filenotify-gio

00:05:14

 
Name Stage Failure
failed
test-filenotify-gio Test
make[2]: *** [xdisp.o] Error 1
Makefile:393: recipe for target 'xdisp.o' failed
make[2]: Leaving directory '/builds/emacs/emacs/src'
make[1]: *** [src] Error 2
Makefile:423: recipe for target 'src' failed
make[1]: Leaving directory '/builds/emacs/emacs'
make: *** [bootstrap] Error 2
Makefile:1116: recipe for target 'bootstrap' failed
ERROR: Job failed: exit code 1
failed
test-all Test
Makefile:393: recipe for target 'xdisp.o' failed
make[2]: *** [xdisp.o] Error 1
make[2]: Leaving directory '/builds/emacs/emacs/src'
Makefile:423: recipe for target 'src' failed
make[1]: *** [src] Error 2
make[1]: Leaving directory '/builds/emacs/emacs'
Makefile:1116: recipe for target 'bootstrap' failed
make: *** [bootstrap] Error 2
ERROR: Job failed: exit code 1