Warning fix. Enter into the spirit of getopt(3) a bit more.

bin/domainname/domainname.c

@@ -63,6 +63,8 @@ main(int argc, char *argv[])
 
 	while ((ch = getopt(argc, argv, "")) != -1)
 		switch (ch) {
+		case '?':
+			/* fall through */
 		default:
 			usage();
 		}