Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

Fix memset sizeofs

Reviewed by: bschmidt

Fix typos - remove duplicate "is".

PR: docs/154934
Submitted by: Eitan Adler <lists at eitanadler.com>
MFC after: 3 days

correctly set the tailq ptr when removing the last item in the q

Approved by: re (kensmith)

Add ieee80211_ageq; a facility for staging packets that require
long-term work before they can be serviced. Packets are tagged and
assigned an age (in seconds) at the point they are added to the
queue. If a packet is not retrieved before it's age expires it is
reclaimed. Tagging can take two forms: a reference to an ieee80211_node
(as happens in the tx path) or an opaque token in cases where there
is no reference or the node structure is not stable (i.e. it's going
to be destroyed).

o add ic_stageq to replace the per-node wds staging queue used for
dynamic wds
o add ieee80211_mac_hash for building ageq tokens; this computes a
32-bit hash from an 802.11 mac address (copied from the bridge)
o while here fix a stray ';' noticed in IEEE80211_PSQ_INIT

Reviewed by: rpaulo
Approved by: re (kensmith)