This adds the RandR 1.2 interface to xwayland and allows modes
advertised by the compositor to be set in an undistructive manner.

With this patch, applications that try to set the resolution will usually
succeed and work while other apps using the same xwayland
instance are not affected at all.

The RandR 1.2 interface will be needed to implement fake-mode-setting and
already makes applications work much cleaner and predictive when a mode
was set.

[hdegoede@redhat.com: Make crtc_set only succeed if the mode matches
 the desktop resolution]

Reviewed-by: Olivier Fourdan <ofourdan@redhat.com>
Acked-by: Michel Dänzer <mdaenzer@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>