peek: track all IP types unconditionally

All other IP types are treated as a single flow between machines.  This
is not optimal, but better than not tracking them at all.  I've heard
stories about making these flows "more unique" by introducing arbitrary
values into the flow tuple instead of empty ports.  Personally, I don't
recommend it.  It puts a lot of strain on the flow tracking algorithm for
little to no benefit.

Also fix a typo that found its way back into the pcapng loader.