- Confirmed that libexpat is built statically and linked with xlsxreader
- May need da7cda3a85 for Windows
- Although libexpat's CMake options are all prefixed with LIBEXPAT_, it also adds some cache entries like SIZE_T (from expat/ConfigureChecks.cmake). Unsure if these affect other libs.
- xlsxio may need additional reconfiguration after moving to add_subdirectory() to find libexpat/libzip on non-Linux platforms.