Copyright (c) 2018 FUJITSU LIMITED. All rights reserved. $COPYRIGHT$ This extension provides the feature of persistent collective communication operations and persistent neighborhood collective communication operations, which is proposed in the MPI Forum as of June 2018. See MPIX_Barrier_init(3) for more details. The code will be moved to the ompi/mpi directory and the MPIX_ prefix will be switch to the MPI_ prefix once the MPI Standard which includes this feature is published.