* Makefile.in (toplev.o): Depend on diagnostic-color.h.
* diagnostic-color.c (should_colorize): Remove _WIN32 version.
(colorize_init): Add argument to _WIN32 version.
* toplev.c: Include diagnostic-color.h.
(process_options): Default to -fdiagnostics-color=auto if
GCC_COLORS env var is in the environment.
* common.opt (fdiagnostics-color=): Add Var and Init.
* doc/invoke.texi (-fdiagnostics-color=): Document that if
GCC_COLORS env var is in the environment, the default is auto
rather than never.
* lib/prune.exp: Add -fdiagnostics-color=never to TEST_ALWAYS_FLAGS.
* lib/c-compat.exp (compat-use-alt-compiler, compat_setup_dfp): Handle
-fdiagnostics-color=never option similarly to
-fno-diagnostics-show-caret option.
From-SVN: r198332
