define all MPI handles with uniquely named handle types

[jeffhammond]

Define the derived type MPI_Status, and define all MPI handles with uniquely named handle types (instead of INTEGER handles, as in the mpi module). This is reflected in the first Fortran binding in each MPI function definition throughout this document (except for the deprecated routines).

[jeffhammond]

I think this is done:

#if !defined(MPICH) && !defined(OPEN_MPI)
#error Sadly, you must compile with an ABIFLAG.
#endif
    type, bind(C) :: MPI_Status
#ifdef MPICH
        integer(kind=c_int)    :: count_lo
        integer(kind=c_int)    :: count_hi_and_cancelled
#endif
        integer(kind=c_int)    :: MPI_SOURCE
        integer(kind=c_int)    :: MPI_TAG
        integer(kind=c_int)    :: MPI_ERROR
#ifdef OPEN_MPI
        integer(kind=c_int)    :: cancelled
        integer(kind=c_size_t) :: ucount
#endif
    end type MPI_Status

    ! MPI_VAL is supposed to be a Fortran integer
    ! but in practice it is a C int, and I do not want
    ! to deal with compiler warnings.
    !
    ! Also, this prevents people from breaking everything
    ! by changing INTEGER to something that is not equivalent
    ! to a C integer.

    type, bind(C) :: MPI_Comm
      integer(kind=c_int) :: MPI_VAL
    end type MPI_Comm

    type, bind(C) :: MPI_Datatype
      integer(kind=c_int) :: MPI_VAL
    end type MPI_Datatype

    type, bind(C) :: MPI_File
      integer(kind=c_int) :: MPI_VAL
    end type MPI_File

    type, bind(C) :: MPI_Group
      integer(kind=c_int) :: MPI_VAL
    end type MPI_Group

    type, bind(C) :: MPI_Info
      integer(kind=c_int) :: MPI_VAL
    end type MPI_Info

    type, bind(C) :: MPI_Message
      integer(kind=c_int) :: MPI_VAL
    end type MPI_Message

    type, bind(C) :: MPI_Op
      integer(kind=c_int) :: MPI_VAL
    end type MPI_Op

    type, bind(C) :: MPI_Request
      integer(kind=c_int) :: MPI_VAL
    end type MPI_Request

    type, bind(C) :: MPI_Win
      integer(kind=c_int) :: MPI_VAL
    end type MPI_Win