net: Use sk_mark for routing lookup in more places

This patch against v2.6.31 adds support for route lookup using sk_mark in some 
more places. The benefits from this patch are the following.
First, SO_MARK option now has effect on UDP sockets too.
Second, ip_queue_xmit() and inet_sk_rebuild_header() could fail to do routing 
lookup correctly if TCP sockets with SO_MARK were used.

Signed-off-by: Atis Elsts <atis@mikrotik.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 58c4b0f..57737b8 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -1119,6 +1119,7 @@
 {
 	struct flowi fl = {
 		.oif = sk->sk_bound_dev_if,
+		.mark = sk->sk_mark,
 		.nl_u = {
 			.ip4_u = {
 				.daddr	= daddr,