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 reverts commit bdb77826d98544ab37741f740dd3516023924b27.
Jack1 is not obsolete and neither jack1 nor jack2 is called 'jackaudio'.
Q: What's the difference between Jack1 and Jack2?
A: http://trac.jackaudio.org/wiki/Q_differenc_jack1_jack2
Currently, we have a 'jack' package with attrname 'jack1d' and a
'jackdbus' package with attrname 'jackaudio'. Make it consistent 'jack1'
and 'jack2' in both package name and attrname.
This aligns the naming with what can be found on the JACK homepage.
Q: what's the difference between jack1 and jack2?
A: http://trac.jackaudio.org/wiki/Q_differenc_jack1_jack2
