[llvm] [GlobalOpt] Handle operators separately when removing GV users (PR #84694)

[Eli Friedman via llvm-commits]

efriedma-quic wrote:

Deleting stores where we can prove the stored value isn't a pointer to an allocation should be fine; it doesn't impact the controversial cases.  (But the current version of the patch is more aggressive, maybe by accident.)

https://github.com/llvm/llvm-project/pull/84694