n5.1.8
fftools/ffmpeg: move some muxing-related code into a separate file
fftools/cmdutils: Add protective () to FLAGS
fftools/cmdutils: split common option handlers into their own file
fftools/ffmpeg: Check read() for failure
ffmpeg: add option -isync
ffmpeg: convert to new channel layout-API
ffmpeg_hw: make hardware selection for filters more user friendly
ffmpeg: add option fps_mode
fftools/ffmpeg_mux_init: Fix double-free on error
fftools/ffplay: Check return of swr_alloc_set_opts2()
fftools/ffprobe: support 2D arrays in print_list_fmt()
fftools/fopen_utf8: support long paths on Windows for fftools
tools/opt_common: Check for malloc failure