Merge r256294 (by adrian) from head:

Merge r256294 (by adrian) from head:

  Fix the "am I a net80211 vap" check for bpf listeners.

  I changed it to use if_transmit a while ago but apparently with monitor
  mode the if_transmit method is overridden.

  This is (mostly) a workaround until a more permanent solution can be
  found.

Candidate for 10.0.

Submitted by:	Patrick Kelsey <kelsey@ieee.org>

git-svn-id: svn://svn.freebsd.org/base/stable/10@259174 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f