OpenCL cosmetics
Add "--stitchable" option for segmented encoding

Stops x264 from attempting to optimize global stream headers, ensuring that
different segments of a video will have identical headers when used with
identical encoding settings.
Fix potential misaligment crash in AVX2 denoise_dct
Fix build with PIC on some systems
Add new color primaries, transfer characteristics, matrix coefficients
Fix possible crash when writing very large filler NALUs

Bitstream-reallocation function didn't handle the case of filler.
test