[PATCH] Add "--git-dir" flag to git-rev-parse

[PATCH] Add "--git-dir" flag to git-rev-parse

Especially when you're deep inside the git repository, it's not all that
trivial for scripts to figure out where GIT_DIR is if it isn't set.

So add a flag to git-rev-parse to show where it is, since it will have
figured it out anyway.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>