a11y: Fix copy-paste error in state flag notification

We weren't checking the removed flag but the added flag for removal
emissions, so what would happen for every state change notification was:
- on state-added, both an "added" and a "removed" event were emitted
- on state-removed, nothing

https://bugzilla.gnome.org/show_bug.cgi?id=694059

gtk/a11y/gtkcellaccessible.c

@@ -412,7 +412,7 @@ _gtk_cell_accessible_state_changed (GtkCellAccessible    *cell,
         atk_object_notify_state_change (object,
                                         state_map[i].atk_state,
                                         !state_map[i].invert);
-      if (added & state_map[i].renderer_state)
+      if (removed & state_map[i].renderer_state)
         atk_object_notify_state_change (object,
                                         state_map[i].atk_state,
                                         state_map[i].invert);