When building with the bundled HDF5 - its targets are exported (when they shouldn't be)

If I build ITK with the built-in, rather than a system, HDF5, then `cmake --install` it - the resulting config file(s) contain HDF5 targets. It can easily cause a build of another project, which `find_package()`'s both ITK and HDF5 independently of ITK, to have clashes. I doubt this is intentional (although - correct me if I'm wrong).

This might also be happening with other bundled libraries. I haven't checked.