examples: Use public Fortran adios2_init signature
examples: Use public Fortran adios2_init signature

The example was calling `adios2_init_config` which is a private name
implementing one variant of the `adios2_init` generic procedure.
Use the public name instead just as applications should.

ornladios/ADIOS2,JasonRuonanWang/ADIOS2,ornladios/ADIOS2,JasonRuonanWang/ADIOS2,ornladios/ADIOS2,ornladios/ADIOS2,JasonRuonanWang/ADIOS2,ornladios/ADIOS2,JasonRuonanWang/ADIOS2,JasonRuonanWang/ADIOS2