Compiling distro releases for macOS

TL;DR version only

• Dependencies that were installed using brew need to be installed using the option --build-bottle, otherwise they may not run on other CPU generations.
• To make mpv compatible with older systems, both ffmpeg and mpv (and ideally all other dependencies) need to be compiled with -mmacosx-version-min=10.8:

ffmpeg: ./configure --extra-cflags="-mmacosx-version-min=10.8" ...

libass: CFLAGS="-mmacosx-version-min=10.8" ./configure ...

mpv: CFLAGS="-mmacosx-version-min=10.8" ./waf configure ...

To bundle the dependency libs, run this in mpv's folder: TOOLS/osxbundle.py build/mpv