Remove obsolete Haskell attribute name compatibility layer.

pkgs/development/haskell-modules/default.nix

@@ -1,7 +1,6 @@
 { pkgs, stdenv, ghc
 , packageSetConfig ? (self: super: {})
 , overrides ? (self: super: {})
-, provideOldAttributeNames ? false
 }:
 
 with ./lib.nix;
@@ -63,9 +62,8 @@ let
 
       };
 
-  compatLayer = if provideOldAttributeNames then import ./compat-layer.nix else (self: super: {});
   commonConfiguration = import ./configuration-common.nix { inherit pkgs; };
 
 in
 
-  fix (extend (extend (extend (extend haskellPackages commonConfiguration) packageSetConfig) overrides) compatLayer)
+  fix (extend (extend (extend haskellPackages commonConfiguration) packageSetConfig) overrides)

pkgs/top-level/all-packages.nix

@@ -3779,7 +3779,6 @@ let
 
   haskellPackages = haskell.packages.ghc7101.override {
     overrides = config.haskellPackageOverrides or (self: super: {});
-    provideOldAttributeNames = config.provideOldHaskellAttributeNames or false;
   };
 
   haxe = callPackage ../development/compilers/haxe { };