[NETFILTER]: nf_queue: fix rerouting after packet mangling

Packets should be rerouted when they come back from userspace, not before.
Also move the queue_rerouters to RCU to avoid taking the queue_handler_lock
for each reinjected packet.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>