[NET] sysctl: make sysctl_somaxconn per-namespace

Just move the variable on the struct net and adjust
its usage.

Others sysctls from sys.net.core table are more
difficult to virtualize (i.e. make them per-namespace),
but I'll look at them as well a bit later.

Signed-off-by: Pavel Emelyanov <xemul@oenvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/net_namespace.h b/include/net/net_namespace.h
index d593611..b62e31f 100644
--- a/include/net/net_namespace.h
+++ b/include/net/net_namespace.h
@@ -39,6 +39,7 @@
 
 	/* core sysctls */
 	struct ctl_table_header	*sysctl_core_hdr;
+	int			sysctl_somaxconn;
 
 	/* List of all packet sockets. */
 	rwlock_t		packet_sklist_lock;