daemon/config: bind to v4 and v6 loopback separately

daemon/lua/config.lua

 -- Listen on localhost
 if not next(net.list()) then
-	local ok, err = pcall(net.listen, {'127.0.0.1', '::1'})
+	local ok, err = pcall(net.listen, '127.0.0.1')
 	if not ok then
-		error('bind to localhost#53 '..err)
+		error('bind to 127.0.0.1#53 '..err)
+	end
+	-- IPv6 loopback may fail
+	ok, err = pcall(net.listen, '::1')
+	if not ok and verbose() then
+		print('bind to ::1#53 '..err)
 	end
 end
 -- Open cache if not set/disabled