python3.pkgs.ijson: enable yail backend

makes parsing a lot faster.

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

@@ -1,4 +1,4 @@
-{ lib, buildPythonPackage, fetchPypi }:
+{ lib, buildPythonPackage, fetchPypi, yajl, cffi, pytestCheckHook }:
 
 buildPythonPackage rec {
   pname = "ijson";
@@ -9,7 +9,11 @@ buildPythonPackage rec {
     sha256 = "1d1003ae3c6115ec9b587d29dd136860a81a23c7626b682e2b5b12c9fd30e4ea";
   };
 
-  doCheck = false; # something about yajl
+  buildInputs = [ yajl ];
+  propagatedBuildInputs = [ cffi ];
+  checkInputs = [ pytestCheckHook ];
+
+  doCheck = true;
 
   meta = with lib; {
     description = "Iterative JSON parser with a standard Python iterator interface";