Allow the macOS GLUT framework to be used automatically in many
cases. Packages that specifically search for freeglut or require its
additional APIs should still explicitly depend on it.
Deliberately skip the Haskell package set, which is mostly
automatically generated, and mupdf, which has its own fork of freeglut.
continuation of #109595
pkgconfig was aliased in 2018, however, it remained in
all-packages.nix due to its wide usage. This cleans
up the remaining references to pkgs.pkgsconfig and
moves the entry to aliases.nix.
python3Packages.pkgconfig remained unchanged because
it's the canonical name of the upstream package
on pypi.
