[INET_SOCK]: Move struct inet_sock & helper functions to net/inet_sock.h

To help in reducing the number of include dependencies, several files were
touched as they were getting needed headers indirectly for stuff they use.

Thanks also to Alan Menegotto for pointing out that net/dccp/proto.c had
linux/dccp.h include twice.

Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
index 14de4eb..e000fa2 100644
--- a/include/net/ip_fib.h
+++ b/include/net/ip_fib.h
@@ -238,6 +238,8 @@
 			       struct net_device *dev, u32 *spec_dst, u32 *itag);
 extern void fib_select_multipath(const struct flowi *flp, struct fib_result *res);
 
+struct rtentry;
+
 /* Exported by fib_semantics.c */
 extern int ip_fib_check_default(u32 gw, struct net_device *dev);
 extern int fib_sync_down(u32 local, struct net_device *dev, int force);