- Update to version 1.7+git.20170612:
* mark the sync syscalls as expensive
* reduce the likelyhood that we call expensive syscalls.

- Update to version 1.7+git.20170525:
* add incoming packets to the correct place in the list.
* add the last op_nr to the childexited message
* add a flag to mark when we're expecting a spawn message.
* only process CHILD_EXITED messages if the opnr is current
* maintain a count of packets processed each scan of the child list.
* childhdr is already set at this point.
* use a single thread to process all child packets
* optimize packet rx list walk
* drop duplicate packets instead of adding them to the list.
* fix up cppcheck signedness warnings
* replace state machine with simpler drain logic