This change essentially amounts to inlining
__CabalEagerPkgConfigWorkaround into haskellPackages.mkDerivation and
applying it automatically for the affected GHC versions. This is a bit
overeager, but the best automatic solution we can come up with for now.
Consequently, we don't need __CabalEagerPkgConfigWorkaround in nixpkgs
anymore nor downstream at least for “standard” haskellPackages builds.
__CabalEagerPkgConfigWorkaround is preserved for now since it is still
necessary if using GHC < 9.4 with Cabal >= 3.10 or cabal-install >= 3.10.
The one thing that may or may not be negatively affected by this change
is ghcWithPackages. I doubt this is a problem in practice though, since
it didn't provide pkg-config in the first place. passthru.env and
shellFor do and work correctly since they rely on mkDerivation.
a83158c7b9