treewide: switch to nativeCheckInputs

checkInputs used to be added to nativeBuildInputs. Now we have
nativeCheckInputs to do that instead. Doing this treewide change allows
to keep hashes identical to before the introduction of
nativeCheckInputs.

pkgs/development/python-modules/enum34/default.nix

@@ -14,7 +14,7 @@ if pythonAtLeast "3.4" then null else buildPythonPackage rec {
     sha256 = "cce6a7477ed816bd2542d03d53db9f0db935dd013b70f336a95c73979289f248";
   };
 
-  checkInputs = [ unittestCheckHook ];
+  nativeCheckInputs = [ unittestCheckHook ];
 
   meta = with lib; {
     homepage = "https://pypi.python.org/pypi/enum34";