5eae50d991
mandatory for IPv6 (so we can't just validate by using connected pcb - we need to allow traffic from unconnected pcb to do pmtud). - if the traffic is validated by xx_ctlinput, allow up to "hiwat" pmtud route entries. - if the traffic was not validated by xx_ctlinput, allow up to "lowat" pmtud route entries (there's upper limit, so bad guys cannot blow up our routing table). sync with kame XXX need to think again about default hiwat/lowat value. XXX victim selection to help starvation case