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.
This is the last 60-esr I believe.
- fixed multiple outputs (saves $out 2MB from $out)
- updated the only patch we carry
- symlinked `js` to `js60`, some packages using spidermonkey expects `js`. Might
make it possible to drop 38 in the future.
This is essentially the same as done in
65f2b0a2a3.
For spidermonkey_38 I set --enable-posix-nspr-emulation, as it would
otherwise complain about a wrong NSPR version and that trick seemed to
be successful in spidermonkey_60 anyway.
