Add {VM.list} so the child VM can easily know its parent
Add {VM.list} so the child VM can easily know its parent

* Current order is spawn order, might become unspecified though.
* Does it needs some locking? std::forward_list::emplace_front()
  should not touch others elements (only the head ptr) so it should be fine.

mistasse/mozart-graal,eregon/mozart-graal,eregon/mozart-graal,eregon/mozart-graal,eregon/mozart-graal,eregon/mozart-graal,mistasse/mozart-graal,mistasse/mozart-graal,mistasse/mozart-graal,mistasse/mozart-graal,eregon/mozart-graal