* add a debug sysctl that just adds a printf() on each received frame.
  This way I can see what the received flow id is.

* add UDP hash types.
Add new INP flags for whether flowid info should be punted up with received
UDP frames.
* Use the current Chelsio t4/t5 firmware RSS key.  The earlier one didn't work
  too well with IPv6 traffic.

* Add UDP hash awareness.
Add 4-tuple UDP hash awareness.
Add a new option for ip_output() - don't assign an outbound flowid
from the inpcb.
Add support for populating received UDP frames with flow and RSS information.
This should work with recvmsg().
* Add socket options for the new UDP flow / RSS information
* Add in the code to ip_output() to control whether to populate the
  flowid on transmit.
* Parse the IP flowid and rss options from sendmsg() and use these
  for outbound UDP transmit.

* For now, flip UDP testing on to 4 tuple.  I'll likely put it back
  to 2-tuple once I fully understand how weird the chelsio/intel
  NICs behave with RX offload and UDP + IP Fragments.