vrele swap and/or root vnode should we fail during mountroot; found by mpech@ and tedu@ ok
vrele swap and/or root vnode should we fail during mountroot; found by mpech@ and tedu@ ok

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