Prevent RRXinerama from activating if PseudoramiX is, so we don't get XINERAMA
listed twice in the list of extensions. I think this is otherwise benign, as
the PseudoramiX XINERAMA gets registered first and thus handles all requests.
Perhaps AddExtension() ought to warn us if the extension name is already
registered?
This appears to be a long-standing bug seen in XQuartz, and now in XWin as well.
Future work: Perhaps since RRXinerama isn't actually doing anything useful but
faking it when we have one screen, it seems that the PseudoramiX code could be
also used in that case.
Signed-off-by: Jon TURNEY <jon.turney@dronecode.org.uk>
Reviewed-by: Colin Harrison <colin.harrison@virgin.net>
95e83ff87a