FTBFS clang-18

[xnox]

2024/08/13 22:51:40 INFO -- Found LibXml2: /usr/lib/libxml2.so (found version "2.13.3")
2024/08/13 22:51:40 WARN CMake Error at /usr/lib/cmake/llvm/LLVMExports.cmake:1683 (message):
2024/08/13 22:51:40 WARN   The imported target "LLVMDemangle" references the file
2024/08/13 22:51:40 WARN
2024/08/13 22:51:40 WARN      "/usr/lib/libLLVMDemangle.a"
2024/08/13 22:51:40 WARN
2024/08/13 22:51:40 WARN   but this file does not exist.  Possible reasons include:
2024/08/13 22:51:40 WARN
2024/08/13 22:51:40 WARN   * The file was deleted, renamed, or moved to another location.
2024/08/13 22:51:40 WARN
2024/08/13 22:51:40 WARN   * An install or uninstall procedure did not complete successfully.
2024/08/13 22:51:40 WARN
2024/08/13 22:51:40 WARN   * The installation package was faulty and contained
2024/08/13 22:51:40 WARN
2024/08/13 22:51:40 WARN      "/usr/lib/cmake/llvm/LLVMExports.cmake"
2024/08/13 22:51:40 WARN
2024/08/13 22:51:40 WARN   but not all the files it references.

So #26103 regressed buildability

As the cmake files reference public paths.... when they really should not.