dhcp6: enabled on infiniband / IPoIB links
capture: fixed to wrap link-layer packet sockets

The default address length in sockaddr_ll is not
enough for infiniband link-layer addresses.
dhcp4: enabled on infiniband / IPoIB links
Merge pull request #206 from mtomaschewski/ipoib-dhcp

Enable DHCPv4 and DHCPv6 on Infiniband