VideoBufferDRMPRIME: extract video buffer interface

[Kwiboo]

Description

This PR moves CVideoBufferDRMPRIME code, extracts a new IVideoBufferDRMPRIME interface and adds Map/Unmap callbacks.
ProcessInfoGBM is also registered with GBM GLES to use Deinterlace Half as fallback on arm devices (current fallback used for rpi, amlogic and android).

@lrusak please test this with your onging vaapi work, gem close is needed or v4l2 buffers is never released.

Motivation and Context

Preparations to be able to use direct-to-plane rendering with sw decoded video.

How Has This Been Tested?

Tested on LibreELEC using Rockchip and Allwinner devices.

Screenshots (if appropriate):

Types of change

• Bug fix (non-breaking change which fixes an issue)
• Clean up (non-breaking change which removes non-working, unmaintained functionality)
• Improvement (non-breaking change which improves existing functionality)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that will cause existing functionality to change)
• Cosmetic change (non-breaking change that doesn't touch code)
• None of the above (please explain below)

Checklist:

• My code follows the Code Guidelines of this project
• My change requires a change to the documentation, either Doxygen or wiki
• I have updated the documentation accordingly
• I have read the Contributing document
• I have added tests to cover my change
• All new and existing tests passed

[lrusak]

Do you want to move the DRM_IOCTL_GEM_CLOSE into the Unmap() function in CVideoBufferDRMPRIME? It is not needed for VAAPI.

[Kwiboo]

I am not sure I want to move it to Unmap() unless keeping it here actually breaks VAAPI. All code references I can find points to that a drmPrimeFDToHandle handle should be DRM_IOCTL_GEM_CLOSE to release the reference hold.

I need to investigate more on how kernel handles reference count for different dma-buf imports, in case we can do some optimization or fix uneven reference count in decoder or kernel. Hopefully result of such investigation can be sent in a follow up PR in near future.