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 switches to explicitly enabling dependency lookups for
optional features (they were not picked up before).
It also enables building of the Parquet command line tools.
Setting setupPyBuildFlags makes builder add an additional target
"build_ext" to setup.py arguments in addition to "bdisst_wheel".
pyarrow's setup.py recently started to try to redo build_ext again which
broke the build.
This replaces standard checkPhase using setup.py that uses pytest-runner
with an explicit call to pytest. One reason to do that is because
setup.py triggers another rebuild when asked to do "test". Another
reason is that there seems to be a conflict between possible imports for
pyarrow: `pwd`/pyarrow vs $out/pyarrow. By some unknown reason this
triggers an import error on hydra and ofborg, but not on my machine. The
solution here is to remove `pwd`/pyarrow, keep the tests and use direct
call to pytest (setup.py needs `pwd`/pyarrow). The added benefit is that
we are now testing what is installed in $out.
