RRGetInfo can be expensive. Don't invoke it when quering Xinerama
information or setting a new CRTC configuration.
(cherry picked from commit b5aa9eb8e6)
Provide a Xinerama implementation when DIX version isn't enabled. This
version exposes each crtc as a separate 'screen' and reports the size of
that patch. The extension also sends ConfigureNotify events to the root
window whenever crtcs change so that applications will re-fetch xinerama
information. This actually works for metacity.
