Make radix lookup on src and dst flow addresses optional
and configurable on per-interface basis.
Remove inline for several functions being called once per
flow (e.g once per 10-20 packets on common traffic flows).
Update manual page to simplify search for BPF data link types.

Sponsored by Yandex LLC

Reviewed by: glebius
Approved by: ae(mentor)
MFC after: 2 weeks