When nothing to git-commit, honor the git-status color setting.

When nothing to git-commit, honor the git-status color setting.

Instead of disabling color all of the time during a git-commit, allow
the user's config preference in the situation where there is nothing
to commit.  In this situation, the status is printed to the terminal
and not sent to COMMIT_EDITMSG, so honoring the status color setting
is expected.

Signed-off-by: Brian Hetro <whee@smaertness.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>