[TCPDIAG]: Implement cheapest way of supporting DCCPDIAG_GETSOCK

With ugly ifdefs, etc, but this actually:

1. keeps the existing ABI, i.e. no need to recompile the iproute2
   utilities if not interested in DCCP.

2. Provides all the tcp_diag functionality in DCCP, with just a
   small patch that makes iproute2 support DCCP.

Of course I'll get this cleaned-up in time, but for now I think its
OK to be this way to quickly get this functionality.

iproute2-ss050808 patch at:

http://vger.kernel.org/~acme/iproute2-ss050808.dccp.patch

Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index f6da932..d3770ae 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -34,6 +34,8 @@
 	.port_rover	= 1024 - 1,
 };
 
+EXPORT_SYMBOL_GPL(dccp_hashinfo);
+
 static int dccp_v4_get_port(struct sock *sk, const unsigned short snum)
 {
 	return inet_csk_get_port(&dccp_hashinfo, sk, snum);