IPSec: Set default unique ID behavior

Prevent an incoming connection request from our peer from
disrupting an ongoing connection.  The default behavior is for
such a connection to replace any ongoing SAs.

TEST=Unit tests + network_VPNConnect.l2tpipsec_psk for regression
and manual: connect to Cisco VPN that originally highlighted this

Change-Id: Ifde31b5988588f894e18a65b2bc8f45c26afb6fe
Reviewed-on: https://chromium-review.googlesource.com/203646
Reviewed-by: Paul Stewart <pstew@chromium.org>
Commit-Queue: Paul Stewart <pstew@chromium.org>
Tested-by: Paul Stewart <pstew@chromium.org>
2 files changed