RFC: KTLS RX software support

[John Baldwin]

I'd like some feedback on my patch to add software KTLS RX support.
There's more detail in the review as well as in my talk at BSDCan
this year (in particular in regards to changes to the receive
socket buffer).  The review is probably the best place to talk
about this vs further followups on the list.  I did post this to
net@ 2 months ago and didn't really get feedback.  I'd like to
merge this into head soon-ish, so if you have feedback, now is the
time to give it.

Thanks!

https://reviews.freebsd.org/D24628

-- 
John Baldwin