IKEv1 pluto test with lots of duplicate packets

When a machine is under load - taking time to get to each packet - the
initiator will timeout out and start sending duplicates for each
request.

This simulates the scenario by overwhelming east's incoming queue with
duplicates of all packets received.  The test then checks that the
duplicates are detected and either replied-to or discarded.  Most
important is the responder detecting duplicate initial requests (and
not creating new states like was happening).
