west initiates ondemand; during IKE_SA_INIT east restarts and initiates

Because west initiated on-demand, and is part way through IKE_SA_INIT,
it is in ROUTED_NEGOTIATING (blocking policy installed) with the IKE
SA #1 as the route owner.

When west then receives east's connection, it needs to transfer
ownership to the new Child SA #3 (IKE SA #2) and then transition to
ROUTED_TUNNEL while installing the full kernel state/policy.
