tests/vnc_perf.html: load from data/multi.js

To go along with addition of performance notes to the website.

tests/vnc_perf.html

@@ -37,7 +37,7 @@
 
     <script src="include/vnc.js"></script>
     <script src="include/playback.js"></script>
-    <script src="data_multi.js"></script>
+    <script src="data/multi.js"></script>
 
     <script>
         var start_time, VNC_frame_data, pass, passes, encIdx,