Clients expect any Xinerama-enabled screen to report at least one
monitor, but with RandR, there may not be any enabled crtcs. In this case,
tell the client that Xinerama is not active.
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.
