Add usage messages for applets without them.

coreutils/hostid.c

@@ -25,6 +25,9 @@
 
 extern int hostid_main(int argc, char **argv)
 {
+	if (argc > 1 && strcmp(argv[1], "--help") == 0)
+		usage(hostid_usage);
+
 	printf("%lx\n", gethostid());
 	return(TRUE);
 }