Add -C to the known options

SRC/error.c

@@ -88,7 +88,7 @@ void
 usage ()
 {
   fprintf (stderr,
-	   "Usage: %s [-v] [-t timeout] [-c] [-d] [-u] [-s size] [-n number] [-w delay] [-h url] [-S] server-name[:port]\n",
+	   "Usage: %s [-v] [-t timeout] [-c] [-d] [-u] [-s size] [-n number] [-w delay] [-h url] [-C] [-S] server-name[:port]\n",
 	   progname);
   exit (1);
 }