superbuild: fix for `llvm-config` searching
Also brings a new numpy and scipy.
- Ben Boeckel: meson-llvm-config-search (common-superbuild!671 (merged))
- Ben Boeckel: ci-xcode-16.1 (common-superbuild!673 (merged))
- Mathieu Westphal: fixup_licenses (common-superbuild!674 (merged))
- Mathieu Westphal: gpl_install_license_lgpl (common-superbuild!672 (merged))
- Ben Boeckel: gperf-cpp17-support (common-superbuild!670 (merged))
- Ben Boeckel: ci-vcvarsall-fix (common-superbuild!669 (merged))