Add API to allow complex applications using the KMS backend
to go almost straight to direct configuration (which is not possible
because Cogl needs to be in charge of buffers and FB objects).
https://bugzilla.gnome.org/show_bug.cgi?id=705837
Reviewed-by: Robert Bragg <robert@linux.intel.com>
(cherry picked from commit 52fb8e1c33d8c83c731c05cee767928fdd5991d7)