conf-libclang on Ubuntu/Debian does not install all needed dependencies

[vprevosto]

On Debian-like distributions, conf-libclang attemps to install libclang-cpp-dev , libclang-dev and llvm-dev, possibly with a specific version number, depending on the exact os-distribution and os-version. However, this will not include cmake rules for libclang, which are distributed in the clang package. I could install conf-clang for that, but this package does not rely on a specific version number, so that there's a high probability to end up with two incompatible versions for clang and libclang-{cpp-}dev, rendering the setup unusable.

Thus, I'm not sure what the best course of action would be. The way Debian splits up llvm/clang related packages clearly does not help in this regard. But it might be easier to maintain the package if the goal is only to install the latest version of all packages, without trying to enforce a specific version (for full disclosure, the opam package I'm interested in, frama-clang, maintains compatibility with clang 12-18, so I guess it would be fine with most distributions)