bpo-38787: C API for module state access from extension methods (PEP 573) (GH-19936)

Module C state is now accessible from C-defined heap type methods (PEP 573).
Patch by Marcel Plch and Petr Viktorin.

Co-authored-by: Marcel Plch <mplch@redhat.com>
Co-authored-by: Victor Stinner <vstinner@python.org>
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 91a645b..33b3459 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -1322,7 +1322,7 @@
                   '3P'                  # PyMappingMethods
                   '10P'                 # PySequenceMethods
                   '2P'                  # PyBufferProcs
-                  '4P')
+                  '5P')
         class newstyleclass(object): pass
         # Separate block for PyDictKeysObject with 8 keys and 5 entries
         check(newstyleclass, s + calcsize("2nP2n0P") + 8 + 5*calcsize("n2P"))