Older games (mostly those based on SDL 1.x) rely on the XVidMode
extension and would refuse to run without.
Add a simple, limited and read-only xvidmode support that reports the
current mode used so that games that rely on xvidmode extension can run
on XWayland.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=87806
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>