mpi/tests/insert_task_cache.c: free allocated memory

mpi/tests/insert_task_cache.c

@@ -101,6 +101,7 @@ void test_cache(int rank, int size, int enabled, size_t *comm_amount)
 		starpu_data_unregister(data_handles[i]);
         }
 
+	free(string);
 	starpu_mpi_comm_amounts_retrieve(comm_amount);
 	starpu_mpi_shutdown();
 	starpu_shutdown();
@@ -139,6 +140,7 @@ int main(int argc, char **argv)
 
 	free(comm_amount_without_cache);
 	free(comm_amount_with_cache);
+	free(string);
 
 	MPI_Finalize();
 	return !result;