[clang] [-Wunsafe-buffer-usage] Fix debug notes for unclaimed DREs (PR #80787)

[via cfe-commits]

jkorous-apple wrote:

> LGTM! I think I did something similar locally when I collected data of unclaimed DREs on those big adopter projects. So I guess the data that we used to find major missing patterns for fix-its is still valid.

So, on one hand it's good that the data are representative but on the other hand if you had discovered this before me you could have saved me some time by sharing the fix :)

https://github.com/llvm/llvm-project/pull/80787