i18n: git-gc "Auto packing the repository" message

Split up the "Auto packing the repository" message into quiet and
verbose variants to make translation easier.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/gc.c

@@ -219,13 +219,13 @@ int cmd_gc(int argc, const char **argv, const char *prefix)
 		 */
 		if (!need_to_gc())
 			return 0;
-		fprintf(stderr,
-			"Auto packing the repository for optimum performance.%s\n",
-			quiet
-			? ""
-			: (" You may also\n"
-			   "run \"git gc\" manually. See "
-			   "\"git help gc\" for more information."));
+		if (quiet)
+			fprintf(stderr, _("Auto packing the repository for optimum performance.\n"));
+		else
+			fprintf(stderr,
+					_("Auto packing the repository for optimum performance. You may also\n"
+					"run \"git gc\" manually. See "
+					"\"git help gc\" for more information."));
 	} else
 		append_option(argv_repack,
 			      prune_expire && !strcmp(prune_expire, "now")