Testing: Make hdf5 test able to run in parallel

In this PR, I extend HDF5 native reader so that now hdf5 tests can read data
by selection(so called hyperslab selection in hdf5).

testing/adios2/engine/hdf5/CMakeLists.txt

@@ -13,4 +13,13 @@ else()
 endif()
 target_link_libraries(TestHDF5WriteRead adios2 gtest ${HDF5_C_LIBRARIES})
 
-gtest_add_tests(TARGET TestHDF5WriteRead)
+if(ADIOS2_HAVE_MPI)
+  target_include_directories(TestHDF5WriteRead PRIVATE ${MPI_C_INCLUDE_PATH})
+  target_link_libraries(TestHDF5WriteRead ${MPI_C_LIBRARIES})
+  set(extra_test_args
+    EXEC_WRAPPER
+      ${MPIEXEC} ${MPIEXEC_NUMPROC_FLAG} ${MPIEXEC_MAX_NUMPROCS}
+  )
+endif()
+
+gtest_add_tests(TARGET TestHDF5WriteRead ${extra_test_args})