This tests the RFC3706 DPD implementation when east crashes.

It is like dpd-01, except west ssh'es into east to crash pluto.
The IPsec SA still survives, because it detects traffic flows
through the host-host tunnel (the DPD probe and ICMP back are
encrypted). Then we ssh into east again to clear the eroute,
breaking phase2, and DPD should declare the peer dead.

dpd should hit, and we should see an infinite amount of keying
attempts - confirming rhbz#848132 is fixed.

(note: the eroute --clear cannot work because west cannot reach east)