Various macOS build fixes

meson: Force pcre2 to be provided by a subproject on macOS

Newer macOS provides /usr/lib/pkgconfig/libpcre2-8.pc which is broken
because it says headers are in /usr/include but that directory doesn't
exist. It can only be used to find the library, which only exists on
newer macOS at /usr/lib/libpcre2-8.dylib, so it's also unusable.

So, force usage of the subproject for glib.

meson: Fix pixman build on ARM64 macOS

https://gitlab.freedesktop.org/pixman/pixman/-/merge_requests/71

meson: Bump required version to 0.63 for diff_files support

Fixes a warning.

meson: Provide fontconfig dep from the subproject

The wrap was doing nothing, because nothing in it was providing the
dep.

meson: Add a native file for macOS x86_64/arm64

This also supports Homebrew and Qt5

git-hooks: Not all OSes ship Python 3 under "python"

macOS doesn't, for instance. Use a shell script to detect which python
to run, which is always available on all OSes due to how git is
packaged on Windows.

meson: Use tarball for graphene instead of git