[clang] Fix to attribute plugins reaching an unreachable (PR #70877)

[Vlad Serebrennikov via cfe-commits]

Endilll wrote:

This was fixed by e11148fda6d8c0eec496463adb46fd6f03a91081
I checked the logs, and exactly the part that this commit fixed is failing.

https://github.com/llvm/llvm-project/pull/70877