Document where in scan_task the scan state can change, and potentially
deal/log a warning if the scan flags change during one of those race
windows.

It's highly likely that I need to actually sit down and replace this
scan infrastructure at some point.  It has some other side effects too -
the scan task is a blocking task scheduled in the net80211 taskqueue;
so drivers that use this taskqueue have other things not run.  Eek.

If you see this printf happen then please let me know!


git-svn-id: svn+ssh://svn.freebsd.org/base/head@275964 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Emulate writes to the IA32_MISC_ENABLE MSR.

PR:		196093
Reported by:	db
Tested by:	db
Discussed with:	grehan
MFC after:	1 week


git-svn-id: svn+ssh://svn.freebsd.org/base/head@275965 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f