Fix crash with "ether dst 1::2" as a filter.

Report an error, rather than crashing, if an IPv6 address is used for
link-layer filtering.
Merge branch 'master' of git+ssh://bpf.tcpdump.org/tcpdump/master/git/libpcap
Merge git://github.com/the-tcpdump-group/libpcap
linktype: add netlink link/dlt type

With Linux 3.11, we have the possibility to debug local netlink traffic
[1] i.e.  the workflow looks like this:

Setup:
  modprobe nlmon
  ip link add type nlmon
  ip link set nlmon0 up

Capture:
  tcpdump -i nlmon0 ...

Teardown:
  ip link set nlmon0 down
  ip link del dev nlmon0
  rmmod nlmon

For pcap interoperability, introduce a common link type for netlink
captures.
Fix tpo.