Log Message:
Update MIMEDefang to 2.35.

Major changes from 2.33 to 2.34:

* The multiplexor can queue requests, which might help throughput on a very busy
  server.
* filter_{relay,sender,recipient} can return "DISCARD" to discard mail.
* Added new filter_unknown_cmd hook so filters can extend the MIMEDefang protocol.
* More fixes to the SpamAssassin interface.
* RAV AntiVirus is no longer supported.
* Non-multiplexor mode is no longer supported.
* Many other minor enhancements and bug fixes.

Major Changes from 2.34 to 2.35

* Bug Fixes