Add :meth:`~xml.parsers.expat.xmlparser.SetAllocTrackerActivationThreshold` and :meth:`~xml.parsers.expat.xmlparser.SetAllocTrackerMaximumAmplification` to :ref:`xmlparser <xmlparser-objects>` objects to prevent use of disproportional amounts of dynamic memory from within an Expat parser. Patch by Bénédikt Tran.