t/helper: mark unused argv/argc arguments

Many test helper programs do not bother to look at argc or argv, because
they don't take any options. In a user-facing program, it's a good idea
to check for unexpected arguments and complain. But for a test helper,
it's not worth the trouble to enforce this.

But we do want to tell the compiler we're OK with ignoring them, to
silence -Wunused-parameter (and obviously we can't get rid of them,
since we have to conform to the usual cmd__foo() interface).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/helper/test-parse-options.c

@@ -263,14 +263,14 @@ int cmd__parse_options_flags(int argc, const char **argv)
 	return parse_options_flags__cmd(argc, argv, test_flags);
 }
 
-static int subcmd_one(int argc, const char **argv, const char *prefix)
+static int subcmd_one(int argc, const char **argv, const char *prefix UNUSED)
 {
 	printf("fn: subcmd_one\n");
 	print_args(argc, argv);
 	return 0;
 }
 
-static int subcmd_two(int argc, const char **argv, const char *prefix)
+static int subcmd_two(int argc, const char **argv, const char *prefix UNUSED)
 {
 	printf("fn: subcmd_two\n");
 	print_args(argc, argv);