Warning: upcoming net80211 churn, be careful!

Hi!

I'm about to start merging in changes from Andriy that change how the
transmit path in net80211 works. Right now it's a holdover from the
old if_start style mechanism - a call to if_start() always consumed
the mbuf, even upon an error. He's changing it so upon error the
caller returns without freeing the mbuf and node reference - that way
net80211 can do something smart (or not, it depends on what he/gleb
get up to in the future.)

I much prefer this model moving forward, so I'm going to start merging
in his code. It's quite possible that there'll be some temporary
whack-a-mole with mbuf / node reference handling, so please bear with
us.

If you track -head and see anything weird with wifi support after
tonight (that wasn't already weird!) then please do email us on the
freebsd-wireless_at_ list.

Thanks!


-a