clang-tidy warns about HDF5 header files

[maurerben]

clang-tidy warns about HDF5 header files:

/home/benedikt/codes/Flash/dev/libs/data_processing/src/read_hdf5.cpp:17:13: warning: Value stored to 'ndims' during its initialization is never read [clang-analyzer-deadcode.DeadStores]
        int ndims = dataspace.getSimpleExtentDims(dims, nullptr);
            ^~~~~   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/benedikt/codes/Flash/dev/libs/data_processing/src/read_hdf5.cpp:17:13: note: Value stored to 'ndims' during its initialization is never read
        int ndims = dataspace.getSimpleExtentDims(dims, nullptr);
            ^~~~~   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Would be nice to turn this warning off.