git-commit.sh: convert run_status to a C builtin

This creates a new git-runstatus which should do roughly the same thing
as the run_status function from git-commit.sh. Except for color support,
the main focus has been to keep the output identical, so that it can be
verified as correct and then used as a C platform for other improvements to
the status printing code.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <junkio@cox.net>

git.c

@@ -252,6 +252,7 @@ static void handle_internal_command(int argc, const char **argv, char **envp)
 		{ "rev-list", cmd_rev_list, RUN_SETUP },
 		{ "rev-parse", cmd_rev_parse, RUN_SETUP },
 		{ "rm", cmd_rm, RUN_SETUP },
+		{ "runstatus", cmd_runstatus, RUN_SETUP },
 		{ "show-branch", cmd_show_branch, RUN_SETUP },
 		{ "show", cmd_show, RUN_SETUP | USE_PAGER },
 		{ "stripspace", cmd_stripspace },