MFC r287649:
Use a common subroutine to fetch and zero protocol stats instead of
duplicating roughly similar code for each protocol.

Merged /head:r256510,256512,257376,257469,260052:

Make 'netstat -i' use getifaddrs(3) instead of kvm(3).

Merged /head:r256510,256512,257376,257469,260052:

Make 'netstat -i' use getifaddrs(3) instead of kvm(3).