If type->tp_getattr is not NULL, don't set has_getattribute to False

In Pyston, has_getattribute got set if __getattribute__ is overridden,
but only tp_getattro is supposed to set __getattribute__ and tp_getattr
will not set it. So add a check to update_one_slot, if type->tp_getattr
is not NULL, don't set has_getattribute to False.

src/capi/typeobject.cpp

@@ -1929,7 +1929,7 @@ static const slotdef* update_one_slot(BoxedClass* type, const slotdef* p) noexce
 
             static BoxedString* getattribute_str = getStaticString("__getattribute__");
             if (p->name_strobj == getattribute_str) {
-                if (descr && descr->cls == &PyWrapperDescr_Type
+                if (type->tp_getattr == NULL && descr && descr->cls == &PyWrapperDescr_Type
                     && ((PyWrapperDescrObject*)descr)->d_wrapped == PyObject_GenericGetAttr)
                     descr = NULL;
             }