Cairo will soon no longer propagate libGL. The DPF submodule needs this:
src/pugl/pugl.h:39:14: fatal error: GL/gl.h: No such file or directory
39 | # include <GL/gl.h>
| ^~~~~~~~~
compilation terminated.
(See also the fix for string-machine, which has the same build issue)
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.