Re: Fix for PR kern/56713

[Taylor R Campbell <campbell+netbsd-tech-kern%mumble.net@localhost>]

Generally looks reasonable to me, assuming it passes the atf tests,
but give hannken@ another few days to review it?

Maybe instead of adding vnode_impl.h to vfs_vnops.c, we can put the
vn_knote_* in vfs_vnode.c or create a new file vfs_knote.c, to avoid
having tentacles of vnode guts creep back into places we successfully
cut them out of before?