[Libva] libva master changes

[Gwenole Beauchesne]

Hi,

The VA/DRM and VA/Wayland APIs were promoted from staging to master.
Only the necessary set of APIs were backported, more advanced usages
will be provided later on. e.g. import of foreign DRM buffers, export
of VA surface or image to a DRM buffer, Wayland rendering capabilities
negotiation, etc.

Further changes are being evaluated. At least, the Android changes are
on the way, and a VA/GLX fix.

Regards,
Gwenole.