Some newer GHC versions have the `package.conf.d` below a `lib` directory.

See https://gitlab.haskell.org/ghc/ghc/-/issues/23476

... on Windows.

The pkg conf file for rts has entries for `haddock-interface` and `haddock-html`
but neither of those actually exist.

In previous GHC versions from nixpkgs, the `otool` setting was referencing a tool in the nix store,
but for GHC 9.6.2 it is just set to "otool" which means it must be in `$PATH`.

The same applies to the `install_name_tool`.

See NixOS/nixpkgs#267250 and https://gitlab.haskell.org/ghc/ghc/-/issues/24211

We work around by using the location of the `ar` command and assume the other tools (from the bintools
package) are also available at the same place.

Trying to build this results in a bus error with ghc-iserv.