macOS really has completely different path conventions that mpv doesn't
take into account and it treats it just like any other old unix-like
system. This means mpv enforces certain conventions on it (like all the
XDG stuff) that doesn't really apply. Since we'd like to use more of
this but at the same time not distrupt mac users even more, let's just
copy and paste the current code to a new file, update the build and call
it a day. This way, the paths of these two platforms can more freely
diverge.
Dudemanguy