Blender Git Loki

Cycles X: fix/improve handling of mismatches between render pass components

Rules are as follows now:
* Single channel pass: can be read into buffer with 1, 3 or 4 channels
* Motion and cryptomatte passes: must be read into buffer with 4 channels
* RGB, RGBA and vector passes: can be read into buffer with 3 or 4 channels

Differential Revision: https://developer.blender.org/D12063