Make sure rt6i_gateway contains nexthop information in
all routes returned from lookup or when routes are directly
attached to skb for generated ICMP packets.

The effect of this patch should be a faster version of
rt6_nexthop() and the consideration of local addresses as
nexthop.
Signed-off-by: NJulian Anastasov <ja@ssi.bg>
Acked-by: NHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>