Support for GPU vendors other than NVIDIA

[gmbeard]

Support for other vendors / manufacturers should be possible as long as the devices support VAAPI H/W encoding.

At a high level, the steps would be...

• Capture the FB to a GPU-resident texture (eglCreateImage with EXT_image_dma_buf_import for Wayland)
• Render the texture(s) to an off-screen buffer
• Supply the off-screen buffer to VAAPI