[clang] scan-build-py: respect LLVM_LIBDIR_SUFFIX like other tools do (PR #108549)

[Nikita Popov via cfe-commits]

nikic wrote:

It looks like you're trying to undo https://github.com/llvm/llvm-project/pull/106612? cc @mgorny 

https://github.com/llvm/llvm-project/pull/108549