Use metapackage to provide better version rolling

Description:

It would be interesting apply the same idea that was done in electron@0a584405 for the llvm suite. Instead of compile the latest version (18) into the llvm package we might think of make symbolic links to the llvm18 folder and provide a meta-package which change the provided llvm version meanwhile it releases newer versions.

Additional info:

electron@0a584405

It would be better for example for issues handling (generally depending on all llvm's or only with a specific version?) and for easier updates, making the upgrade more controllable

Steps to do it:

  1. Create an llvm18 repository (I think https://gitlab.archlinux.org/archlinux/packaging/packages/llvm18)
  2. Compile successfully llvm18 there
  3. Remove the compilation of llvm18 from this repository, do proper symlinks