message: Fix warnings for the Kokkos example
diff: } \
  } while (false)
  -int BPWrite(const std::string fname, const size_t N, int nSteps,
  +int BPWrite(const std::string fname, const size_t N, size_t nSteps,
  const std::string engine)
  {
  int rank, size;
  @@ -86,18 +86,16 @@ int BPWrite(const std::string fname, const size_t N, int nSteps,
  return 0;
  }
  -int BPRead(const std::string fname, const size_t N, int nSteps,
  +int BPRead(const std::string fname, const size_t N, size_t nSteps,
  std::string engine)
  {
  - int rank, size;
  + int rank;
  #if ADIOS2_USE_MPI
  int provided;
  MPI_Init_thread(&argc, &argv, MPI_THREAD_MULTIPLE, &provided);
  MPI_Comm_rank(MPI_COMM_WORLD, &rank);
  - MPI_Comm_size(MPI_COMM_WORLD, &size);
  #else
  rank = 0;
  - size = 1;
  #endif
  // Create ADIOS structures
  #if ADIOS2_USE_MPI
  @@ -148,7 +146,8 @@ int main(int argc, char **argv)
  {
  const std::vector<std::string> list_of_engines = {"BPFile", "BP5"};
  const size_t N = 6000;
  - int nSteps = 10, ret = 0, rank = 0;
  + size_t nSteps = 10;
  + int ret = 0, rank = 0;
  #if ADIOS2_USE_MPI
  int provided;
  MPI_Init_thread(&argc, &argv, MPI_THREAD_MULTIPLE, &provided);
  