e8cdbd2ea7
This makes for a chroma plane of 2x2. The SIMD versionf of generic downscalers assume that the width and height is at least 2, since it does an unconditional loop for the body of the image, and a separate step for the last pixel and last row. The SIMD versions assume that (width-1) and (height-1) are larger than zero. This fixes spurious crashes in EncodeDecodeTestAPI.SetOptionEncParamExt.