o mark rx frames including FCS in the payload with the
IEEE80211_RADIOTAP_F_FCS flag
o remove hack to copy 802.11 headers with padding out of line; instead mark
the frames with IEEE80211_RADIOTAP_F_DATAPAD and require applications to
do the work
o split precalculated radiotap flags into tx+rx now that they can be different
Note the full usefulness of these changes depends on updates to applications
that process radiotap data.