Look up keys to wired-in pkg keys at runtime instead of generating a YAML

[Ericson2314]

I think this worked for me doing my Nix stuff, and it seems generally simpler.

[luite]

This would defeat the purpose of the current setup, where the exact version bundled in the ghcjs-boot libraries (or inside the ghcjs repo in case of ghcjs-th and ghcjs-prim) needs to be loaded.

Let me know if you need help making things work on Nix, but unfortunately changing the lookup to runtime is not a good idea at the moment (at least until I'm sure that we can guarantee that the correct packages are loaded)

[Ericson2314]

The idea is Nix would guarantee that the proper version would be loaded. Maybe this can be a compile time option to be used by Nix but not normal builds?

In any event, I consider converting patches to workspaces a higher priority for my build system work than this.