i18n: index-pack: use plural string instead of normal one

Git could output "completed with 1 local objects", but in this
case using "object" instead of "objects" is the correct form.

Use Q_() instead of _().

Signed-off-by: Vasco Almeida <vascomalmeida@sapo.pt>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/index-pack.c

@@ -1250,7 +1250,9 @@ static void conclude_pack(int fix_thin_pack, const char *curr_pack, unsigned cha
 		       nr_unresolved * sizeof(*objects));
 		f = sha1fd(output_fd, curr_pack);
 		fix_unresolved_deltas(f);
-		strbuf_addf(&msg, _("completed with %d local objects"),
+		strbuf_addf(&msg, Q_("completed with %d local object",
+				     "completed with %d local objects",
+				     nr_objects - nr_objects_initial),
 			    nr_objects - nr_objects_initial);
 		stop_progress_msg(&progress, msg.buf);
 		strbuf_release(&msg);