IPV6 update

zerotierone/osdep/WindowsEthernetTap.cpp

@@ -861,6 +861,14 @@ void WindowsEthernetTap::scanMulticastGroups(std::vector<MulticastGroup> &added,
 	_multicastGroups.swap(newGroups);
 }
 
+NET_IFINDEX WindowsEthernetTap::interfaceIndex() const
+{
+	NET_IFINDEX idx = -1;
+	if (ConvertInterfaceLuidToIndex(&_deviceLuid,&idx) == NO_ERROR)
+		return idx;
+	return -1;
+}
+
 void WindowsEthernetTap::threadMain()
 	throw()
 {