Fixed a crash in the FDM supports gizmo when the wipe tower was shown

The crash happened during showing/hiding of volumes, which historically assumed to always run in SLA mode and so did not expect to encounter the wipe tower.

src/slic3r/GUI/GLCanvas3D.cpp

@@ -1743,6 +1743,8 @@ void GLCanvas3D::toggle_sla_auxiliaries_visibility(bool visible, const ModelObje
     m_render_sla_auxiliaries = visible;
 
     for (GLVolume* vol : m_volumes.volumes) {
+        if (vol->composite_id.object_id == 1000)
+            continue; // the wipe tower
         if ((mo == nullptr || m_model->objects[vol->composite_id.object_id] == mo)
         && (instance_idx == -1 || vol->composite_id.instance_id == instance_idx)
         && vol->composite_id.volume_id < 0)