Recursively disable builds that depend on a known broken package

[peti]

hackage2nix has the know-how to decide that some package foo cannot compile (on a certain platform), because it depends on some other package bar that doesn't compile (on that platform). We just don't use that information yet.

Caveat: it's possible that this feature backfires when a package has optional dependencies that aren't actualy used during the build, i.e. dependencies used only for testing.