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/ip_output.c b/net/ipv4/ip_output.c
index 9fe5d7b..f989518 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -335,6 +335,7 @@
 
 		{
 			struct flowi fl = { .oif = sk->sk_bound_dev_if,
+					    .mark = sk->sk_mark,
 					    .nl_u = { .ip4_u =
 						      { .daddr = daddr,
 							.saddr = inet->saddr,