haskell: Fix depending on libs with internal libs on darwin.

Thanks to @hamishmack for the pointer.

Fixes #33149.

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

@@ -243,7 +243,7 @@ stdenv.mkDerivation ({
     # libraries) from all the dependencies.
     local dynamicLinksDir="$out/lib/links"
     mkdir -p $dynamicLinksDir
-    for d in $(grep dynamic-library-dirs "$packageConfDir/"*|awk '{print $2}'); do
+    for d in $(grep dynamic-library-dirs "$packageConfDir/"*|awk '{print $2}'|sort -u); do
       ln -s "$d/"*.dylib $dynamicLinksDir
     done
     # Edit the local package DB to reference the links directory.