fsnotify: Open handle with O_PATH, v2

Otherwise if the mark is set up on link we end
with -ELOOP error trying to open it. Thus, use
O_PATH pointing the kernel that we're not going
to read/write this descriptor.

Repored-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Acked-by: Andrew Vagin <avagin@parallels.com>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>