Shareable bufmgr objects

[Lionel Landwerlin]

Hi there,

Here is a small modification I had to make to get buffers shared
between Mesa and LibVA on Chrome OS. This is required to have
refcounting properly between the 2 API otherwise, Mesa might end up
calling exit() when the kernel tells it that one of the buffer object
used in a batch buffer is invalid :

http://cgit.freedesktop.org/mesa/mesa/tree/src/mesa/drivers/dri/i965/intel_batchbuffer.c#n282

Thanks,

-
Lionel