[NETFITLER]: Add nfnetlink layer.

Introduce "nfnetlink" (netfilter netlink) layer.  This layer is used as
transport layer for all userspace communication of the new upcoming
netfilter subsystems, such as ctnetlink, nfnetlink_queue and some day even
the mythical pkttables ;)

Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
new file mode 100644
index 0000000..3629d3d
--- /dev/null
+++ b/net/netfilter/Kconfig
@@ -0,0 +1,5 @@
+config NETFILTER_NETLINK
+       tristate "Netfilter netlink interface"
+       help
+         If this option is enabled, the kernel will include support
+         for the new netfilter netlink interface.