Don't make failure to -nolisten fatal

If failing to disable a protocol specified by -nolisten failed, we'd
throw a FatalError and bomb startup entirely.  From poking at xtrans, it
looks like the only way we can get a failure here is because we've
specified a protocol name which doesn't exist, which probably doesn't
constitute a security risk.

And it makes it possible to start gdm even though you've built with
--disable-tcp-transport.

Signed-off-by: Daniel Stone <daniel@fooishbar.org>
Reviewed-by: Alan Coopersmith <alan.coopersmith@oracle.com>
Signed-off-by: Keith Packard <keithp@keithp.com>

os/utils.c

@@ -757,8 +757,8 @@ ProcessCommandLine(int argc, char *argv[])
         else if (strcmp(argv[i], "-nolisten") == 0) {
             if (++i < argc) {
                 if (_XSERVTransNoListen(argv[i]))
-                    FatalError("Failed to disable listen for %s transport",
-                               argv[i]);
+                    ErrorF("Failed to disable listen for %s transport",
+                           argv[i]);
             }
             else
                 UseMsg();