Blender Git Loki

Fix missing samples count pass when using tiles

Samples count pass is normalized to the overall number of samples.
This means that we need to store actual value of the samples in the
tile buffer file.

A bit annoying to pull all those settings to BufferParams and need
to find a more generic solution, but for now this is easiest and a
quickest solution.

Differential Revision: https://developer.blender.org/D12597