message: mpidummy: fix some bugs when getting sizeof MPI_Datatype
diff: @@ -140,19 +140,19 @@ int MPI_Gather(const void *sendbuf, int sendcnt, MPI_Datatype sendtype,
  switch (recvtype)
  {
  case MPI_CHAR:
  - nrecv = sizeof(char);
  + n = sizeof(char);
  break;
  case MPI_INT:
  - nrecv = sizeof(int);
  + n = sizeof(int);
  break;
  case MPI_UNSIGNED:
  - nrecv = sizeof(unsigned int);
  + n = sizeof(unsigned int);
  break;
  case MPI_UNSIGNED_LONG:
  - nrecv = sizeof(unsigned long);
  + n = sizeof(unsigned long);
  break;
  case MPI_UNSIGNED_LONG_LONG:
  - nrecv = sizeof(unsigned long long);
  + n = sizeof(unsigned long long);
  break;
  default:
  return MPI_ERR_TYPE;
  @@ -230,7 +230,7 @@ int MPI_Scatter(const void *sendbuf, int sendcnt, MPI_Datatype sendtype,
  switch (recvtype)
  {
  case MPI_INT:
  - nrecv = sizeof(int);
  + n = sizeof(int);
  break;
  default:
  return MPI_ERR_TYPE;
  