Test Reauthentication of CREATE_CHILD_SA IPsec SA sharing IKE SA.

- WEST establishes 2 connections

  IKE SA #1(A)
  Child SA #2(A), #3(B)

- because all of WEST's connections are configured with reauth=yes;
  replace is triggered after 40 seconds

  + the Child SAs Child SAs #2(A), #3(B) are torn down in OLD2NEW
    order (i.e., B, A) (NEW2OLD would be better but less conservative)

    Since they have +UP they are submitted to libevent for revival in
    the order B, A.

  + the IKE SA #1(A) is torn down

  + a new IKE SA #4(A) is initiated

- the reviving B, and A are added to IKE SA #4(A)'s pending queue

  WARNING:

  Since libevent makes no ordering guarentees, it may run these as
  either A, B; or B, A making the test unstable.
