Remove post-process hook that disables hspec's test suite.
Remove post-process hook that disables hspec's test suite.

Suggested by @Fuuzetsu in https://github.com/NixOS/nixpkgs/issues/8664.

gridaphobe/cabal2nix,psibi/cabal2nix,bennofs/cabal2nix,spencerjanssen/cabal2nix,Fuuzetsu/cabal2nix