changes include:
- do not chase header if ip/ip6 datagram is framgented, and it is not the
first fragment
- u_short -> u_int16_t
- buffer boundary checks, including sprintf -> snprintf
- cleanup truncated packet cases
- pull tcpdump.org enhancements/corrections for RIP, IPv6 options, ICMPv6,
OSPFv3, IPv4 options, BGP
there are a lot of local/conflicting changes. we'd gradually decrease
# of diffs by synchronizing both ends, and then move to src/dist/tcpdump
and reachover makefile.