[pktgen] Version 3.3.8 pushed

It appears I created a bug in Pktgen on version 3.3.5 and I have fixed the bug. The bug was pktgen would only send a couple million packets then stop sending.

Please pull the latest version, which should work with DPDK 17.08-rc2

If any more bugs, enhancements or suggestions please send and email.

Regards,
Keith