The sys/netipsec policy-cache (added by Jason Thorpe as a rewrite of
the KAME per-PCB policy cache) assumes that policy-cacheable PCBs
always has a non-NULL inph_sp in the common PCB header. So we must
do all the per-PCB policy cache calls when either (KAME) IPSEC, or
FAST_IPSEC is defined. ``Make it so''.
We can now support non-IPsec'ed IPv6 traffic, when both
``options FAST_IPSEC'' and ``options INET6'' are configured.