Direct scanout to flip frames from client on screen without composition

[Xtr126]

Using a direct scanout path to flip frames on screen without composition remains unsolved.

• As I have tried, minigbm fails to import externally allocated dmabuf graphic buffers from clients such as vkcube
• If that could be solved then we could take the dmabuf from client surface's buffer and create an AHardwareBuffer for it by creating a native handle with the attributes, using cros gralloc headers.
• Then it would be a matter of sending the AHardwareBuffer to SurfaceFlinger using ASurfaceTransaction APIs with AHARDWAREBUFFER_USAGE_COMPOSER_OVERLAY flag set so that it could be presented in a hardware composer overlay.
  Related: Certain clients cannot render, black screen #3

[Xtr126]

I will have to look into minigbm codebase and find out what's stopping me from doing that and then try to get around with it by modifying minigbm.