This commit disables the library-for-ghci flag passed to
`Setup configure` in the Haskell generic-builder.nix file.
This stops the HSfoo.o file from being built. Building this
HSfoo.o file caused doctest to take an extremely long time
to load dependencies when running.
This is a follow-up from https://github.com/NixOS/nixpkgs/pull/58743.