by Mike Grupenhoff <kashmir@umiacs.umd.edu> in PR #2485.
While I'm here, do some long-overdue cleanup, including function prototypes,
and update for modern libkvm interfaces.
semantics and interface now follow the iostat/vmstat standard for
statistics reporting.
man page rewritten to match new semantics and interface. now shared.
stats from the network interface struct, not their now-nonexistant
old locations. i came up with the fix, prompted by Rich Murphey's
solution, which simply removed the printing of those statistics entirely.