This significantly improves fastd performance, to the level it was before
Barrier Breaker.

This now includes the previously added patch.

Besides other issues, this should fix an integer overflow breaking IPv6 address
aquisition after a runtime of 50 days.

This also removes our mac80211 backport for now, as the version found in
Attitude Adjustment is up-to-date.

This *should* fix the build on non-Linux systems like MacOS X.

This should fix the TX power problems with the TL-WR841N/ND v9.

Only compile tested, might not work.