Support OpenMPI in MPI-IO adapter

[ChristopherHogan]

Currently we rely on MPICH internals. The following updates to MPI_Status happen in 3 places in mpiio.cc:

mpi_status->count_hi_and_cancelled = 0;
mpi_status->count_lo = ret;

This won't compile with OpenMPI.

[hariharan-devarajan]

@ChristopherHogan I can't find any way to check if OpenMPI or MPICH is used in the code.

One Approach: We will have to have CMAKE options for the adapter to use MPICH or OpenMPI.

Do you have any recommendations?

[hyoklee]

If I use openmpi-4.1.1, I get the following error.

In file included from /scr/hyoklee/src/hermes/adapter/mpiio/mpiio.cc:13:0:
/scr/hyoklee/src/hermes/adapter/mpiio/mpiio.h:29:10: fatal error: mpio.h: No su\
ch file or directory
 #include <mpio.h>
          ^~~~~~~~

openmpi-4.1.1 is used by the latest Spack [email protected] package.