[NETFILTER]: Fix routing of REJECT target generated packets in output chain

Packets generated by the REJECT target in the output chain have a local
destination address and a foreign source address. Make sure not to use
the foreign source address for the output route lookup.

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