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* GCC 11 now warns about this.

* gcc 10 and 11 at -O3 recognize that the previous version was not
  allowed to change results_2, because no pointer to it escaped. This
  changed source still triggers the original bug and is robust to the
  gcc optimizer double guessing the original programs intent.

* Compiling on daint verified that 20.1 is still affected too,
  hence I assume every version between 20.1 and 20.11 is also.

* Also write to counter argument as soon as possible to reduce number
  of variables to save across calls.

* This will enable saving MPI_Type_dup calls later on, where
  ownership can be simply transferred.