Add _PyType_GetModuleByDef (GH-22835)

See https://mail.python.org/archives/list/capi-sig@python.org/thread/T3P2QNLNLBRFHWSKYSTPMVEIL2EEKFJU/ for discussion.

https://bugs.python.org/issue42100
diff --git a/Include/cpython/object.h b/Include/cpython/object.h
index 875a600..0db53c3 100644
--- a/Include/cpython/object.h
+++ b/Include/cpython/object.h
@@ -296,6 +296,8 @@ PyAPI_FUNC(PyObject *) _PyObject_LookupSpecial(PyObject *, _Py_Identifier *);
 PyAPI_FUNC(PyTypeObject *) _PyType_CalculateMetaclass(PyTypeObject *, PyObject *);
 PyAPI_FUNC(PyObject *) _PyType_GetDocFromInternalDoc(const char *, const char *);
 PyAPI_FUNC(PyObject *) _PyType_GetTextSignatureFromInternalDoc(const char *, const char *);
+struct PyModuleDef;
+PyAPI_FUNC(PyObject *) _PyType_GetModuleByDef(PyTypeObject *, struct PyModuleDef *);
 
 struct _Py_Identifier;
 PyAPI_FUNC(int) PyObject_Print(PyObject *, FILE *, int);