The bundled libxkbcommon has hardcoded paths from the CI build
environment baked into the library. Set XKB_CONFIG_ROOT to point
to the bundled XKB data instead.
Similarly, set FONTCONFIG_FILE and FONTCONFIG_PATH to use the
bundled fontconfig configuration.
This fixes the segfault on startup caused by libxkbcommon trying
to load XKB data from a non-existent CI runner path.
2165610e9a