Use a Cell rather than unifying the results of the benchmark
Use a Cell rather than unifying the results of the benchmark

* Unification is expensive for very long lists.
* Avoid holding 2 results in memory at the same time.

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