AUDIT: Spawn kernel thread to list filter rules.

If we have enough rules to fill the netlink buffer space, it'll 
deadlock because auditctl isn't ever actually going to read from the 
socket until we return, and we aren't going to return until it 
reads... so we spawn a kernel thread to spew out the list and then
exit.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>