message: examples: Remove unused variable from IO_h5mixer
diff: #define DEFAULT_CONFIG mix.xml
  #define DEFAULT_CONFIG_STR str(DEFAULT_CONFIG)
  -static int rank_saved;
  adios2::ADIOS *ad = nullptr;
  // std::shared_ptr<adios2::Engine> h5mixerWriter;
  adios2::Engine h5mixerWriter;
  @@ -31,8 +30,6 @@ adios2::Variable<unsigned int> varGndx;
  IO::IO(const Settings &s, MPI_Comm comm)
  {
  - rank_saved = s.rank;
  -
  m_outputfilename = MakeFilename(s.outputfile, ".h5");
  /*ad = new adios2::ADIOS(std::string(DEFAULT_CONFIG_STR), comm);
  