Fix exit drop and packet stats; other cleanups.

The first commit sync's the "live device" stats with the dag stats for proper logging of packets and drops at the default logging level on exit.

The second commitment is stylistic only, using a consistent style to the code.  The 3rd is self explanatory.

- PR build: https://buildbot.suricata-ids.org/builders/jasonish/builds/61
- PR pcaps: https://buildbot.suricata-ids.org/builders/jasonish-pcap/builds/15