message: insitumpi: Replace ADIOSMPI.h with direct mpi.h inclusion
  The insitumpi code is built only when using a real MPI, so we can use it
  directly.
diff: #define ADIOS2_ENGINE_INSITUMPI_INSITUMPIREADER_H_
  #include "adios2/common/ADIOSConfig.h"
  -#include "adios2/common/ADIOSMPI.h"
  #include "adios2/core/ADIOS.h"
  #include "adios2/core/Engine.h"
  #include "adios2/helper/adiosComm.h"
  #include "adios2/helper/adiosFunctions.h"
  #include "adios2/toolkit/format/bp/bp3/BP3Deserializer.h"
  +#include <mpi.h>
  +
  namespace adios2
  {
  namespace core
  