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.
I am using sentencepiece in a downstream application where I want to
minimize the resulting closures. This commit makes changes to make
sentencepiece a leaner dependency:
- Split the outputs, so that the binaries/headers do not end up in the
transitive closure in a library dependency.
- Add the `withGPerfTools` option, which is enabled by default, to
make it possible to disable the gperftools dependency. According to
the sentencepiece README, this dependency gives a 10-40% performance
improvement. But in many cases this is overshadowed by the neural
networks that use piece identifiers as input anyway.
