Fix MPI memory leak

For reproducing sums, the allocated MPI operation was not freed.

src/utils/ReproducibleSumMPI.hpp

@@ -43,6 +43,8 @@ allReduceReproducibleSum(const ReproducibleScalarSum<ArrayT, BoolArrayT>& s)
   BinType sum_bin = zero;
   MPI_Allreduce(&local_bin, &sum_bin, 1, mpi_bin_type, mpi_bin_sum_op, parallel::Messenger::getInstance().comm());
 
+  MPI_Op_free(&mpi_bin_sum_op);
+
   return sum_bin;
 }
 
@@ -68,6 +70,8 @@ allReduceReproducibleSum(const ReproducibleTinyVectorSum<ArrayT, BoolArrayT>& s)
   BinType sum_bin = zero;
   MPI_Allreduce(&local_bin, &sum_bin, 1, mpi_bin_type, mpi_bin_sum_op, parallel::Messenger::getInstance().comm());
 
+  MPI_Op_free(&mpi_bin_sum_op);
+
   return sum_bin;
 }
 
@@ -93,6 +97,8 @@ allReduceReproducibleSum(const ReproducibleTinyMatrixSum<ArrayT, BoolArrayT>& s)
   BinType sum_bin = zero;
   MPI_Allreduce(&local_bin, &sum_bin, 1, mpi_bin_type, mpi_bin_sum_op, parallel::Messenger::getInstance().comm());
 
+  MPI_Op_free(&mpi_bin_sum_op);
+
   return sum_bin;
 }