We need to return a persistent request.
`ompi_request_empty` is not a persistent request.
Signed-off-by: KAWASHIMA Takahiro <t-kawashima@jp.fujitsu.com>
(cherry picked from commit 69901a515697485cf56599e206dcfb74228e7ca2)
Until the MPI Forum decides to add the persistent collective
communication request feature to the MPI Standard, these functions
are supported through MPI extensions with the `MPIX_` prefix.
Only C bindings are supported currently.
Signed-off-by: KAWASHIMA Takahiro <t-kawashima@jp.fujitsu.com>
