ipv4: Fix wrong order of ip_rt_get_source() and update iph->daddr.

This patch fix a bug which introduced by commit ac8a4810 (ipv4: Save
nexthop address of LSRR/SSRR option to IPCB.).In that patch, we saved
the nexthop of SRR in ip_option->nexthop and update iph->daddr until
we get to ip_forward_options(), but we need to update it before
ip_rt_get_source(), otherwise we may get a wrong src.
Signed-off-by: NLi Wei <lw@cn.fujitsu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/ip_options.c

@@ -573,8 +573,8 @@ void ip_forward_options(struct sk_buff *skb)
 		}
 		if (srrptr + 3 <= srrspace) {
 			opt->is_changed = 1;
-			ip_rt_get_source(&optptr[srrptr-1], skb, rt);
 			ip_hdr(skb)->daddr = opt->nexthop;
+			ip_rt_get_source(&optptr[srrptr-1], skb, rt);
 			optptr[2] = srrptr+4;
 		} else if (net_ratelimit())
 			printk(KERN_CRIT "ip_forward(): Argh! Destination lost!\n");