the flags method of the ac97 host interface is optional.  check that it not NULL before using it. fixes crash reported by jmc@
the flags method of the ac97 host interface is optional.  check that
it not NULL before using it.
fixes crash reported by jmc@

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars