Bug 1547730 - Compensate for __builtin__ use in files accessed by py3 r=glandium

Differential Revision: https://phabricator.services.mozilla.com/D28105

--HG--
extra : moz-landing-system : lando

python/mozbuild/mozbuild/configure/__init__.py

@@ -4,12 +4,12 @@
 
 from __future__ import absolute_import, print_function, unicode_literals
 
-import __builtin__
 import inspect
 import logging
 import os
 import re
 import six
+from six.moves import builtins as __builtin__
 import sys
 import types
 from collections import OrderedDict