The patch you posted undoes a change I made to bpf_mtap() that
has catchpacket call either memcpy() or bpf_memcpy(), depending
on whether or not the entire packet is in a single mbuf.

bpf_measure() should really be a m_length() function and put in
either mbuf.h or uipc_mbuf.c, not bpf.c, along with a prototype
in the appropriate place.

And, btw, a prototype for bpf_deliver() is also missing.

i.e. your patch needs more work before integrating into NetBSD.
Also, see what Sam said about its raison d'etre.

Darren