[clang] [Clang] More aggressively mark this* dead_on_return in destructors (PR #183347)

[Florian Hahn via cfe-commits]

https://github.com/fhahn commented:

I've tracked down a potential mis-compile to this change, when using a pool allocator.

A reduced version of the code that illustrates the issue is https://clang.godbolt.org/z/eb36n1vr4

Not sure if there is anything in the repro that makes it UB that I missed.

https://github.com/llvm/llvm-project/pull/183347