haskell-tar: use older version for builds with GHC < 7.6.x.

pkgs/development/haskell-modules/configuration-ghc-7.0.x.nix

···
   # Needs hashable on pre 7.10.x compilers.
   nats = addBuildDepend super.nats self.hashable;
 
+  # Newer versions require bytestring >=0.10.
+  tar = super.tar_0_4_1_0;
+
 }

pkgs/development/haskell-modules/configuration-ghc-7.2.x.nix

···
   # Needs hashable on pre 7.10.x compilers.
   nats = addBuildDepend super.nats self.hashable;
 
+  # Newer versions require bytestring >=0.10.
+  tar = super.tar_0_4_1_0;
+
 }

pkgs/development/haskell-modules/configuration-ghc-7.4.x.nix

···
   # Avoid depending on tasty-golden.
   monad-par = dontCheck super.monad-par;
 
+  # Newer versions require bytestring >=0.10.
+  tar = super.tar_0_4_1_0;
+
 }