Update ghcjs

I noticed that updating `development/compilers/ghcjs/1.0.1.nix` didn't give me an updated ghcjs.

It seems that `development/tools/haskell/ghcjs/default.nix` is the one that needs updating.

What's the difference between them?

Note that currently building ghcjs gives the following error: https://github.com/ghcjs/ghcjs/issues/275