WIP: Export EGLImage to DMABuf instead of GEM
These patches aim to fix the usage of totem on wayland for gallium (AMDGPU).
Instead of exporting the EGLImages to GEM buffers, we export them to DMABuf, because AMD gallium driver only can import DMABufs for creating VA surfaces. As far as I tested, there's no regression for intel-vaapi-driver. I'm don't know if we have tested totem with intel's media-driver. We should confirm.
@biswasab can you test these patches?
An open question is: should we remove all the GEM related code in gstreamer-vaapi? including the (now unused) EGL_MESA_drm_image extension?