Partially sync magdir/sniffer from the file distribution on astron.com,
adds pcap-ng files and some more link-layer types for pcap. Not an exact
merge because they're using "use" which we don't curre

Partially sync magdir/sniffer from the file distribution on astron.com,
adds pcap-ng files and some more link-layer types for pcap. Not an exact
merge because they're using "use" which we don't currently support.
ok nicm@ jasper@

show more ...

Update file to 4.21.

tested by ian@ sthen@

OK ian@, "move ahead with it" deraadt@

merge back two chunks that are different here

merge in new magic from file 4.09. Mostly from Bruno Rohee

add missing tcpdump capture types; aldo@nullcube.com

Updated from NetBSD.