[Swan-dev] state m/c 3of3: add a ICOOKIE+ZERO_COOKIE hash table

[Andrew Cagney]

The start of process_v2_packet is a whole chunk of logic intended to
deal with something (I"m not sure what as some bits are clearly
wrong).  For instance:

- it is refering to IKE_I when it should refer to MSG_R for some of
the state lookups
(the early IKE_R vs MSG_R changes address this)

- the intial responder ignores INIT re-transmits when in state R1 (it
should reply)

The issue here is that it needs to be able the responder in R1 state
using just the ICOOKIE.  Like the initiator in I1 state.

My change is to add a second hash table hashed by just RCOOKIE.  And,
for INIT packets use that.