These packages originating from OpenWRT don't see regular releases, so
this bumps them to their latest commits.
Also implements some suggestions like removing spaces from cmakeFlags
and replacing the legacy lgpl21 license with the appropriate lgpl21Only.
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.
