GitLab

This improves readability a lot and prevent us from reinventing the wheel.

    use size_t instead of int to represent sizes
    removes unused parameters from:
        block_BytestreamInit()
        mpeg4_audio/LOASSyncInfo()
        cinepak/cinepak_Getv1()
        speex/SendPacket()
        subsass/ParseColor()
        ffmpeg/postprocess/InitPostproc() & PostprocPict()
        dvbsub/YuvaYuvp() & encode_pixel_line_{2,4,8}bp()
        faad/DoReordering()

vlc_block_helper.h:
    use size_t, removes unused parameter from block_BytestreamInit()

struct filter_t:
    removes unused parameters from pf_picture_link() & pf_picture_unlink()
    
cmml: fix a segfault (p_item isn't an input item, despite the name) present for some months, proving that nobody did use that code ?

strnlen: export its VLC pendant properly and check its existance in cc.c. Fixes the compilation onDarwin

Missing some cases that I could not test.
Also ffmpeg/chroma.c is locked, so I can but leave it broken.
Fix is for the remaining modules is obvious and the issue is easy to detect.

The rollup and paint on mode is not really good (a lot of flicker) but
I don't see how to fix it (the subtitle is updated as soon as a new
character is added).