edj_viewer: fix the residual spacer parts when mirror mode is applied

Summary:
When mirror mode is toggled, the position of spacer parts in preview is not changed.
So I added the code to update spacer parts.

@T3367

Test Plan:
1. laucnch enventor
2. added the spacer to preview
3. toggle mirror mode more than two times.
4. see the spacer parts whether it is updated or not

Reviewers: Hermet, Jaehyun_Cho, NikaWhite

Differential Revision: https://phab.enlightenment.org/D3835

src/lib/edj_viewer.c

@@ -891,4 +891,6 @@ view_mirror_mode_update(view_data *vd)
    if (!vd || !vd->layout) return;
    edje_object_mirrored_set(vd->layout,
                             enventor_obj_mirror_mode_get(vd->enventor));
+   dummy_obj_update(vd->layout);
+   part_obj_geom_cb(vd, evas_object_evas_get(vd->layout), vd->part_obj, NULL);
 }