[FFmpeg-devel] Add LoongArch SIMD optimization in swscale lib.

[Hao Chen]

[PATCH v1 1/3] swscale/la: Optimize hscale functions with lasx.
[PATCH v1 2/3] swscale/la: Add yuv2rgb_lasx.c and rgb2rgb_lasx.c
[PATCH v1 3/3] swscale/la: Add output_lasx.c file.