netmap: packet stall

netmap: packet stall

- Fix packet processing stall under high load when using netmap in IPS mode.
- Detect and generate Fatal Error exit for rare case when hardware NIC exposes
unmatched RX/TX queue counts. This is rare, but would result in some traffic
bypassing Suricata since it assumes NIC queue counts are symmetrical.
- Fix instance of missing unlock call for netmap device list when exiting due
to an error condition.
- Clean up existing code comments and add additional ones to better document
the new netmap v14 API code.