[clang] [llvm] [Coroutines] Drop dead instructions more aggressively in addMustTailToCoroResumes() (PR #85271)

[Chuanqi Xu via cfe-commits]

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+// This tests that the symmetric transfer at the final suspend point could happen successfully.
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ChuanqiXu9 wrote:

nit: I feel slightly better to add a link to the github page.

https://github.com/llvm/llvm-project/pull/85271