client: Clean up old registry on reconnect

Change-Id: Idcaf1aaef59529f0cb49c552418a434f7d449d7b
Reviewed-by: David Edmundson <davidedmundson@kde.org>

src/plugins/platforms/wayland/qwaylanddisplay.cpp

@@ -472,6 +472,8 @@ void QWaylandDisplay::reconnect()
         mSyncCallback = nullptr;
     }
 
+    if (object())
+        wl_registry_destroy(object());
     mDisplay = wl_display_connect(nullptr);
     if (!mDisplay)
         _exit(1);