randr: only respected changed on the protocol screen

We don't want to know about changes on the non-protocol screen,
we will fix up setchanged to make sure non-protocol screens update
the protocol screens when they have a change.

Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Dave Airlie <airlied@redhat.com>

randr/randr.c

@@ -506,7 +506,7 @@ RRTellChanged(ScreenPtr pScreen)
         mastersp = pScrPriv;
     }
 
-    if (pScrPriv->changed) {
+    if (mastersp->changed) {
         UpdateCurrentTimeIf();
         if (mastersp->configChanged) {
             mastersp->lastConfigTime = currentTime;