This fixes the failure to find CLANG_LIBRARIES on debian, which packages
the relevant .so file at these paths:
libclang-cpp18: /usr/lib/llvm-18/lib/libclang-cpp.so.18.1
libclang-cpp18: /usr/lib/x86_64-linux-gnu/libclang-cpp.so.18.1
libclang-cpp18: /usr/lib/x86_64-linux-gnu/libclang-cpp.so.18
(The latter two paths are symlinks to the first.)