Abandoning ifnet work

[Kyle Evans]

Hi,

Just a heads up... I had been doing some ifnet work that I'm now
abandoning because the review process for this area is simply not
worth it: D22691[0]. I'd quite like to see someone else pick it up and
finish out, though... I've been running with some success an earlier
version of this that coordinates if_vmove() and vnet shutdown's
evacuation of ifnets with if_detach() to render some of the common
epair/vnet races harmless.

Feel free to tag me for reviewing if you want to pick it up.

Thanks,

Kyle Evans

[0] https://reviews.freebsd.org/D22691