add DOVE extensions for VXLAN

This patch provides extensions to VXLAN for supporting Distributed
Overlay Virtual Ethernet (DOVE) networks. The patch includes:

	+ a dove flag per VXLAN device to enable DOVE extensions
	+ ARP reduction, whereby a bridge-connected VXLAN tunnel endpoint
		answers ARP requests from the local bridge on behalf of
		remote DOVE clients
	+ route short-circuiting (aka L3 switching). Known destination IP
		addresses use the corresponding destination MAC address for
		switching rather than going to a (possibly remote) router first.
	+ netlink notification messages for forwarding table and L3 switching
		misses

Changes since v2
	- combined bools into "u32 flags"
	- replaced loop with !is_zero_ether_addr()
Signed-off-by: David L Stevens <dlstevens@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/if_link.h

@@ -302,6 +302,10 @@ enum {
 	IFLA_VXLAN_AGEING,
 	IFLA_VXLAN_LIMIT,
 	IFLA_VXLAN_PORT_RANGE,
+	IFLA_VXLAN_PROXY,
+	IFLA_VXLAN_RSC,
+	IFLA_VXLAN_L2MISS,
+	IFLA_VXLAN_L3MISS,
 	__IFLA_VXLAN_MAX
 };
 #define IFLA_VXLAN_MAX	(__IFLA_VXLAN_MAX - 1)