ipv4: Fetch route saddr from flow key in inet_sk_reselect_saddr().

Now that output route lookups update the flow with
source address selection, we can fetch it from
fl4->saddr instead of rt->rt_src
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/af_inet.c

@@ -1122,7 +1122,7 @@ static int inet_sk_reselect_saddr(struct sock *sk)
 
 	sk_setup_caps(sk, &rt->dst);
 
-	new_saddr = rt->rt_src;
+	new_saddr = fl4.saddr;
 
 	if (new_saddr == old_saddr)
 		return 0;