when doing user mounts, inherit the MNT_NOEXEC flag from the covered vnode's mount point. this makes it impossible for a user to bypass the noexec protection of a mount point by null-mounting it on top of itself.
when doing user mounts, inherit the MNT_NOEXEC flag from the covered
vnode's mount point. this makes it impossible for a user to bypass the
noexec protection of a mount point by null-mounting it on top of itself.

ok tedu@ millert@

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