Revert "haskell: workaround for bug with dynamic libraries on darwin"

This reverts commit 19e2e7290a.

See the correct fix in aa64994b48a29ea8d12323942f1743fa4133527a

General purpose solution will be once we implement
https://github.com/NixOS/nixpkgs/issues/21624

pkgs/development/haskell-modules/generic-builder.nix

@@ -244,41 +244,9 @@ stdenv.mkDerivation ({
     runHook postConfigure
   '';
 
-  # The darwin pre/post build sections are a workaround https://github.com/haskell/cabal/issues/4183
-  # It seems like --extra-lib-dirs from the previous steps is not detected properly,
-  # to work around this we build using a DYLD_LIBRARY_PATH and fixup the build afterwards.
   buildPhase = ''
     runHook preBuild
-    ${optionalString stdenv.isDarwin ''
-      local inputClosure=""
-      for i in $propagatedNativeBuildInputs $nativeBuildInputs; do
-        findInputs $i inputClosure propagated-native-build-inputs
-      done
-      local -a inputLibs=()
-      for p in $inputClosure; do
-        if [ -d "$p/lib/${ghc.name}/package.conf.d" ]; then
-          continue
-        fi
-        if [ -d "$p/lib" ]; then
-          inputLibs+="$p/lib"
-        fi
-      done
-
-      for lib in $inputLibs; do
-        export DYLD_LIBRARY_PATH="$lib:''${DYLD_LIBRARY_PATH:+:$DYLD_LIBRARY_PATH}"
-      done
-    ''}
     ${setupCommand} build ${buildTarget}${crossCabalFlagsString}
-    ${optionalString stdenv.isDarwin ''
-      unset DYLD_LIBRARY_PATH
-
-      local outputLib=dist/build/*-ghc${ghc.version}.dylib
-      for lib in $inputLib/*.dylib; do
-        for name in $(otool -L $outputLib | awk '$1 ~ /^'$(basename lib)'/ {print $1}' | cat); do
-          install_name_tool -change $name $lib $outputLib
-        done
-      done
-    ''}
     runHook postBuild
   '';