Indirect definition of _ADIOS2 and _HDF5 macros for lib piof

[dqwu]

In tests/general/util/pio_tutil.F90, several macros, namely _NETCDF4,
_NETCDF, _PNETCDF, _ADIOS2, and _HDF5, are utilized.

In the case of NetCDF/PnetCDF libraries, the macros _NETCDF4,
_NETCDF, and _PNETCDF are directly defined for lib piof in
src/flib/CMakeLists.txt:

#===== NetCDF-Fortran =====
if (WITH_NETCDF)
  find_package (NetCDF ${NETCDF_FORTRAN_MIN_VER_REQD} COMPONENTS Fortran)
  if (NetCDF_Fortran_FOUND)
    message(STATUS "NetCDF Fortran library dependencies: ${NetCDF_Fortran_LIBRARIES}")
    ...
    target_compile_definitions (piof
      PUBLIC _NETCDF)
    ...
    if (EXISTS ${NetCDF_Fortran_INCLUDE_DIR}/netcdf_par.h)
      target_compile_definitions (piof
        PUBLIC _NETCDF4)
...

#===== PnetCDF =====
if (WITH_PNETCDF)
  find_package (PnetCDF ${PNETCDF_MIN_VER_REQD} COMPONENTS Fortran)
  if (PnetCDF_FOUND)
    message(STATUS "PnetCDF Fortran library dependencies: ${PnetCDF_Fortran_LIBRARIES}")
    ...
    target_compile_definitions (piof
      PUBLIC _PNETCDF)

However, for ADIOS2/HDF5 libraries, where no Fortran components
are available, the direct definition of _ADIOS2 and _HDF5 for lib
piof in src/flib/CMakeLists.txt is not feasible.

To overcome this limitation, a workaround is to define these macros
for lib pioc in src/clib/CMakeLists.txt. Consequently, they are indirectly
defined for lib piof.

For _HDF5, it will be something like:

#===== HDF5-C =====
if (WITH_HDF5)
  find_package (HDF5 COMPONENTS HL C)
  if (HDF5_C_FOUND)
    ...
    target_compile_definitions (pioc
      PUBLIC _HDF5)

The current definition of _ADIOS2 for lib adios2pio-nm-lib in
tools/adios2pio-nm/CMakeLists.txt may need to be relocated to
src/clib/CMakeLists.txt to ensure consistency for lib pioc:

if (ADIOS2_FOUND)
  target_compile_definitions (adios2pio-nm-lib
    PUBLIC _ADIOS2)

It is worth noting that this workaround introduces a minor issue
related to duplicate macro definitions. On one hand, _ADIOS2 and
_HDF5 are defined using CMake's target_compile_definitions() for
lib pioc. On the other hand, they are also explicitly defined in
pio.h of lib pioc:

#if PIO_USE_ADIOS
  #define _ADIOS2 1
#endif
#if PIO_USE_HDF5
  #define _HDF5 1
#endif