builtin/checkout.c: mark strings for translation

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

builtin/checkout.c

@@ -662,7 +662,7 @@ static void update_refs_for_switch(const struct checkout_opts *opts,
 		}
 	} else if (new->path) {	/* Switch branches. */
 		if (create_symref("HEAD", new->path, msg.buf) < 0)
-			die("unable to update HEAD");
+			die(_("unable to update HEAD"));
 		if (!opts->quiet) {
 			if (old->path && !strcmp(new->path, old->path)) {
 				if (opts->new_branch_force)