Re-generate all Haskell packages with the latest version of cabal2nix.

This change brings support for building and running the regressions test suites.

pkgs/development/libraries/haskell/ReadArgs/default.nix

@@ -1,4 +1,4 @@
-{ cabal, systemFilepath, text }:
+{ cabal, hspec, systemFilepath, text }:
 
 cabal.mkDerivation (self: {
   pname = "ReadArgs";
@@ -7,6 +7,7 @@ cabal.mkDerivation (self: {
   isLibrary = true;
   isExecutable = true;
   buildDepends = [ systemFilepath text ];
+  testDepends = [ hspec systemFilepath text ];
   meta = {
     homepage = "http://github.com/rampion/ReadArgs";
     description = "Simple command line argument parsing";