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.
Unneded args.something replaced with
args: with args;
line. After this line args is the only place where we can recieve variables from.
Also removed several
buildInputs = [];
lines.
svn path=/nixpkgs/branches/stdenv-updates/; revision=10429
