Cleanup GHC and think about GHC in corepkgs

[jonringer]

#180 highlights that GHC still has a lot of existing baggage from how it's maintained upstream.

In addition, it's very difficult to actually "package" GHC without introducing a few dozen hackage packages, and that complexity is tackled in https://github.com/ekala-project/haskell-pkgs.

I say all this because I'm starting to be more open to just moving all haskell related stuff; including the ghc binary dists, into the haskell overlay. Nothing in the repo is a haskell package because of the bootstrapping issue. Other than shellcheck, there's not really a haskell utilty which is central to development, building software, or deployments.

[qweered]

We can have a minimum amount of Haskell packages needed for bootstrap in corepks, like we already do with Perl, python and texlive (needs big debloat). Shellcheck is pretty important software cause I expected it to be used to check all shell scripts in ekala ecosystem, including corepkgs's ones

[jonringer]

That is valid... hmmm, okay, partial import of haskellPackages, just enough for GHC I'm fine with