pad-monitor: improve serialized event checks

If the event was already found at the first position of the array, it
shouldn't be searched on the rest of it.

This removes lots of false positives.

validate/gst/validate/gst-validate-pad-monitor.c

@@ -1472,8 +1472,8 @@ gst_validate_pad_monitor_event_probe (GstPad * pad, GstEvent * event,
           || GST_EVENT_TYPE (event) == GST_EVENT_TYPE (next_event->event)) {
         g_ptr_array_remove_index (monitor->serialized_events, 0);
       }
-    }
-
+    } else {
+      /* if the event is not the first, it might be out of order */
       for (i = 0; i < monitor->serialized_events->len; i++) {
         SerializedEventData *stored_event =
             g_ptr_array_index (monitor->serialized_events, i);
@@ -1487,6 +1487,7 @@ gst_validate_pad_monitor_event_probe (GstPad * pad, GstEvent * event,
         }
       }
     }
+  }
 
   /* This so far is just like an event that is flowing downstream,
    * so we do the same checks as a sinkpad event handler */