hackage-packages.nix: update Haskell package set

This update was generated by hackage2nix v20160308-3-g8057d11-dirty using the following inputs:

  - Nixpkgs: https://github.com/NixOS/nixpkgs/commit/840709b4a328998017b85479a9fce233d486c180
  - Hackage: https://github.com/commercialhaskell/all-cabal-hashes/commit/ab666959f09636bea6aa2b57a3941cfd3c211471
  - LTS Haskell: https://github.com/fpco/lts-haskell/commit/6c45757bda6547fb7bb847982c4b50b41bc31c07
  - Stackage Nightly: https://github.com/fpco/stackage-nightly/commit/d8a2cae77932579034f28ce11e4bfed4db1aa65a