don't block display events when time is set backwards

Bug: 10184

Signed-off-by: Andreas Müller <schnitzeltony@googlemail.com>

src/display.c

@@ -757,7 +757,7 @@ myDisplayUpdateCurrentTime (DisplayInfo *display, XEvent *ev)
             break;
     }
 
-    if ((timestamp != (guint32) CurrentTime) && TIMESTAMP_IS_BEFORE(display->current_time, timestamp))
+    if ((timestamp != (guint32) CurrentTime))
     {
         display->current_time = timestamp;
     }