Sort expected files to fix Cygwin testing

Author: mgorny

unittests/allplatformstests.py

@@ -3167,7 +3167,7 @@ def test_python_build_config_extensions(self):
                         self.build()
                         with open(intro_installed_file) as f:
                             intro_installed = json.load(f)
-                        self.assertEqual(expected_files, list(intro_installed))
+                        self.assertEqual(sorted(expected_files), sorted(intro_installed))
                         self.wipe()
 
     def __reconfigure(self):