use strpbrk(3) to search for characters from a given set

We can check if certain characters are present in a string by calling
strchr(3) on each of them, or we can pass them all to a single
strpbrk(3) call.  The latter is shorter, less repetitive and slightly
more efficient, so let's do that instead.

Signed-off-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/show-branch.c

@@ -536,7 +536,7 @@ static void append_one_rev(const char *av)
 		append_ref(av, &revkey, 0);
 		return;
 	}
-	if (strchr(av, '*') || strchr(av, '?') || strchr(av, '[')) {
+	if (strpbrk(av, "*?[")) {
 		/* glob style match */
 		int saved_matches = ref_name_cnt;