status: disable translation when --porcelain is used

"git status --branch --porcelain" displays the status of the branch
(ahead, behind, gone), and used gettext to translate the string.

Use hardcoded strings when --porcelain is used, but keep the gettext
translation for "git status --short" which is essentially the same, but
meant to be read by a human.

Reported-by: Anarky <ghostanarky@gmail.com>
Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

wt-status.h

@@ -50,6 +50,7 @@ struct wt_status {
 	enum commit_whence whence;
 	int nowarn;
 	int use_color;
+	int no_gettext;
 	int display_comment_prefix;
 	int relative_paths;
 	int submodule_summary;