builtin-verify-tag: fix -v option parsing

Since the C rewrite, "git verify-tag -v" just does nothing instead of
printing the usage message with an error. This patch fix the regression.
Signed-off-by: NOlivier Marin <dkr@freesurf.fr>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

builtin-verify-tag.c

@@ -92,14 +92,15 @@ int cmd_verify_tag(int argc, const char **argv, const char *prefix)
 
 	git_config(git_default_config, NULL);
 
-	if (argc == 1)
-		usage(builtin_verify_tag_usage);
-
-	if (!strcmp(argv[i], "-v") || !strcmp(argv[i], "--verbose")) {
+	if (argc > 1 &&
+	    (!strcmp(argv[i], "-v") || !strcmp(argv[i], "--verbose"))) {
 		verbose = 1;
 		i++;
 	}
 
+	if (argc <= i)
+		usage(builtin_verify_tag_usage);
+
 	/* sometimes the program was terminated because this signal
 	 * was received in the process of writing the gpg input: */
 	signal(SIGPIPE, SIG_IGN);