Copy stable/9 to releng/9.3 as part of the 9.3-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head to stable/9 as part of 9.0-RELEASE release cycle.

Approved by: re (implicit)

Disconnect sun4v architecture from the three.

Some files keep the SUN4V tags as a code reference, for the future,
if any rewamped sun4v support wants to be added again.

Reviewed by: marius
Tested by: sbruno
Approved by: re

(Mostly) teach ath_rate_sample about MCS rates.

This is just the bare minimum needed to teach ath_rate_sample to try
and handle MCS rates. It doesn't at all attempt to find the best
rate by any means - it doesn't know anything about the MCS rate
relations, TX aggregation or any of the much sexier 11n stuff
that's out there.

It's just enough to transmit 11n frames and handle TX completion.

It shouldn't affect legacy (11abg) behaviour.

Obtained from: rpaulo@