hdf5 flags for Summit config file

The `MW_LINK_FLAGS ` in the Summit config file may need to be updated as
```
export MW_LINK_FLAGS="`${OLCF_NETCDF_C_ROOT}/bin/nc-config --libs` -L/ccs/home/imn/yaml/lib64 -lyaml-cpp -L${OLCF_PARALLEL_NETCDF_ROOT}/lib -lpnetcdf -lyaml-cpp -lhdf5_hl -lhdf5"
```