When sandboxing is enabled, the hook tries to run `install_name_tool`
and fails because the system one is inaccessible. Having it use
`targetPrefix` allows it to find and use the cross-install_name_tool.
Adds the static overlay that can be used to build Nixpkgs statically.
Can be used like:
nix build pkgsStatic.hello
Not all packages build, as some rely on dynamic linking.
