Re-apply r190640.

Re-apply r190640.

- Restore local change to include <net/bpf.h> inside pcap.h.
This fixes ports build problems.
- Update local copy of dlt.h with new DLT types.
- Revert no longer needed <net/bpf.h> includes which were added
as part of r334277.

Suggested by:	antoine@, delphij@, np@
MFC after:	3 weeks
Sponsored by:	Mellanox Technologies