this fixes the issue that on some filesystems, you cannot recursively
remove a directory when you hold a lock on a file inside (e.g. nfs/cifs)
it is not really backwards compatible (so during an upgrade, there
could be two daemons have the lock), but since the locking was
broken before (see previous patch) it should not really matter
(also it seems very unlikely that someone will trigger this)
Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>