Revert "Merge pull request #27209 from nc6/nc/haskell-multiple-out"

This reverts commit dfb0f25484, reversing
changes made to 7f8ff02437. These changes broke
the ghcWithPackages wrapper:

    nix-shell -p "haskellPackages.ghcWithPackages (ps: [ps.mtl])" --run "ghc-pkg list mtl"
    /nix/store/szz84j5k1dy3jdashis6ws28d8l8zxxb-ghc-8.0.2-with-packages/lib/ghc-8.0.2/package.conf.d
        (no packages)

pkgs/development/haskell-modules/lib.nix

@@ -142,8 +142,4 @@ rec {
   overrideSrc = drv: { src, version ? drv.version }:
     overrideCabal drv (_: { inherit src version; editedCabalFile = null; });
 
-  hasNoBinOutput = drv: overrideCabal drv (drv: { enableSeparateBinOutput = false; });
-
-  installOutputs = drv: outputs: overrideCabal drv
-    (drv: { outputsToInstall = outputs; });
 }