Minor fixes for pf_walk_header6(): - Fragment offset is in network byte order. - Check for legal short fragments before calling pf_pull_hdr() to   avoid bogus reason accounting. - When checking wether the protocol header is within the fragment,   count the IPv6 payload length relative to the end of the IPv6 header. ok henning@
Minor fixes for pf_walk_header6():
- Fragment offset is in network byte order.
- Check for legal short fragments before calling pf_pull_hdr() to
  avoid bogus reason accounting.
- When checking wether the protocol header is within the fragment,
  count the IPv6 payload length relative to the end of the IPv6 header.
ok henning@

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars