Implemented Martin's suggestion to clear the free lists during the garbage collection of the highest generation.

Include/methodobject.h

@@ -85,6 +85,8 @@ typedef struct {
     PyObject    *m_module; /* The __module__ attribute, can be anything */
 } PyCFunctionObject;
 
+PyAPI_FUNC(int) PyCFunction_ClearFreeList(void);
+
 #ifdef __cplusplus
 }
 #endif