kill some useless getter simcalls

kill some useless getter simcalls

They were rather misleading since they did not do any simcall,
actually. The code around the getters of data in the actors is still
somehow magical:

smpi_switch_data_segment((static_cast<smpi_process_data_t>((static_cast<simdata_process_t>(comm->dst_proc->data)->data))->index));

I love this one. Once I'm done, it will become:

smpi_switch_data_segment(comm->dst_proc->extension<SmpiActorExt>()->index);

I pretend that it is clearer. Maybe to me only? :-3