Copyright (c) 2018      FUJITSU LIMITED.  All rights reserved.

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This extension provides the feature of persistent collective communication
operations and persistent neighborhood collective communication operations,
which is planned to be included in the next MPI Standard after MPI-3.1 as
of Nov. 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.
