apparmor: fix disconnected bind mnts reconnection

commit f2e561d190da7ff5ee265fa460e2d7f753dddfda upstream.

Bind mounts can fail to be properly reconnected when PATH_CONNECT is
specified. Ensure that when PATH_CONNECT is specified the path has
a root.

BugLink: http://bugs.launchpad.net/bugs/1319984



Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Seth Arnold <seth.arnold@canonical.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Willy Tarreau <w@1wt.eu>