Blender Git Loki

FFmpeg: Fix H264 lossless render not lossless

While encoder parameters for lossless encoding are set correctly,
output is not lossless due to pixel format being set to
`AV_PIX_FMT_YUV420P` which is inherently lossy due to chroma subsampling.

This was reported in T61569 and was merged to T57397, but there were
2 bugs - one for encoding and one for decoding.

Set pixel format to `AV_PIX_FMT_YUV444P` when rendering lossless H264
files. This format isn't available in `codec->pix_fmts[0]` and it looks,
that it has to be hard-coded.

Reviewed By: sergey

Differential Revision: D11458