`glxgears` doesn't work for me as X-Fowarding test

On https://www.rc.ucl.ac.uk/docs/Wiki_Export/X-Forwarding/#checking-your-setup there's a suggestion to use glxgears to check that X-forwarding is working. glxgears doesn't work for me on a macOS host:

$ glxgears
libGL error: No matching fbConfigs or visuals found
libGL error: failed to load driver: swrast
X Error of failed request:  BadValue (integer parameter out of range for operation)
  Major opcode of failed request:  149 (GLX)
  Minor opcode of failed request:  3 (X_GLXCreateContext)
  Value in failed request:  0x0
  Serial number of failed request:  36
  Current serial number in output stream:  38

and it took me a little while to work out that X-forwarding was working fine, but it was glxgears that wasn't. Checking by launching xterm worked fine though, so maybe worth removing the suggstion to check using glxgears?

Start with the X-Forwarding documentation page linked in the issue and locate the section suggesting glxgears for checking the setup. Update the guidance so it does not present glxgears as the check, and consider the reported xterm check; done means the documentation no longer misleads macOS users about whether X-forwarding works.