Enable zero buffer copy method for wayland VDA.

1080p video playback is quite unsmooth on VTC-1010, with only 15 render fps
and ~70% CPU usage. Root cause is current code spend too much time to
put output vasurface to GL texture for more than 25ms for each
frame, due to buffer copy between driver and user space. As a result,
GPU swap buffer operations are not executed timely and then blocks
render side composting.

This CL enables a zero buffer copy solution that will put vasurface to
CL texture inside GPU process. It creates an EGL image through
EGL_DRM_BUFFER_MESA target, then binds the EGL image to GL texture. All
the operations are without CPU interaction.

Local test result shows it gets 31 render fps and ~25% CPU usage for 1080p playback.
It also benefits other resolution video playback. 

BUG = XWALK-2069
why destroy egl_image_, if it's already null? What's the case that it falls in this conditional?