alias.c: mark split_cmdline_strerror() strings for translation

This function can be part of translated messages. To make sure we
don't have a sentence with mixed languages, mark the strings for
translation, but only use translated strings in places we know we will
output translated strings.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/merge.c

@@ -577,7 +577,7 @@ static void parse_branch_merge_options(char *bmo)
 	argc = split_cmdline(bmo, &argv);
 	if (argc < 0)
 		die(_("Bad branch.%s.mergeoptions string: %s"), branch,
-		    split_cmdline_strerror(argc));
+		    _(split_cmdline_strerror(argc)));
 	REALLOC_ARRAY(argv, argc + 2);
 	MOVE_ARRAY(argv + 1, argv, argc + 1);
 	argc++;