[clang] [NFC] Updating Debug Info generation for 'this' (PR #119445)

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joaosaffran wrote:

@llvm-beanz @dwblaikie I've built a bootstrap version of clang with and without this change, the binary output was identical for both builds (check them with `diff`), please let me know if there is something else you might need me testing

https://github.com/llvm/llvm-project/pull/119445