Refactored some of the Py_TRACE_REFS code. New private API function

_Py_AddToAllObjects() that simply inserts an object at the front of
the doubly-linked list of all objects.  Changed PyType_Ready() (the
 closest thing we've got to a choke point for type objects) to call
that.

Include/object.h

@@ -582,6 +582,7 @@ PyAPI_FUNC(void) _Py_NewReference(PyObject *);
 PyAPI_FUNC(void) _Py_ForgetReference(PyObject *);
 PyAPI_FUNC(void) _Py_Dealloc(PyObject *);
 PyAPI_FUNC(void) _Py_PrintReferences(FILE *);
+PyAPI_FUNC(void) _Py_AddToAllObjects(PyObject *);
 
 #else
 /* Without Py_TRACE_REFS, there's little enough to do that we expand code