Define new macro Py_InitModule3(name, methods, doc) which calls
Py_InitModule4() with appropriate arguments.
diff --git a/Include/modsupport.h b/Include/modsupport.h
index 5c00241..442394c 100644
--- a/Include/modsupport.h
+++ b/Include/modsupport.h
@@ -111,6 +111,10 @@
 	Py_InitModule4(name, methods, (char *)NULL, (PyObject *)NULL, \
 		       PYTHON_API_VERSION)
 
+#define Py_InitModule3(name, methods, doc) \
+	Py_InitModule4(name, methods, doc, (PyObject *)NULL, \
+		       PYTHON_API_VERSION)
+
 extern char *_Py_PackageContext;
 
 #ifdef __cplusplus