ffmpeg: revert yuv2yuvX conversion to assembly
This causes VTK's AVI writer to output striped output. The suspicion is that the non-assembly codepath is not tested well as the superbuild builds FFmpeg without yasm support.
This causes VTK's AVI writer to output striped output. The suspicion is that the non-assembly codepath is not tested well as the superbuild builds FFmpeg without yasm support.