Upgrade hashable to version 1.2.x.

This change in the GHC 7.6.3 profile violates Haskell Platform, but it fixes
many builds that would not succeed otherwise (such as Trifecta). Overriding
hashable locally in an expression is out of question: the package is used
virtually everywhere.

pkgs/development/libraries/haskell/haskell-platform/2013.2.0.0.nix

@@ -30,6 +30,7 @@ cabal.mkDerivation (self : {
     cp ${self.cabalFile} $sourceRoot/${self.pname}.cabal
     cp ${self.setupFile} $sourceRoot/Setup.hs
     touch $sourceRoot/LICENSE
+    sed -i -e 's|hashable  *==1.1.2.5,|hashable,|' $sourceRoot/${self.pname}.cabal
   '';
   noHaddock = true;
   meta = {

pkgs/top-level/haskell-packages.nix

@@ -190,7 +190,7 @@ let result = let callPackage = x : y : modifyPrio (newScope result.finalReturn x
     GLUT         = self.GLUT_2_4_0_0;
     GLURaw       = self.GLURaw_1_3_0_0;
     haskellSrc   = self.haskellSrc_1_0_1_5;
-    hashable     = self.hashable_1_1_2_5;
+    hashable     = self.hashable_1_2_1_0;       # not HP (1.1.2.5), but fixes many builds
     html         = self.html_1_0_1_2;
     HTTP         = self.HTTP_4000_2_8;
     HUnit        = self.HUnit_1_2_5_2;