[llvm] [InstCombine] Add user-count bailout to isAllocSiteRemovable (PR #190347)

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

Compile-time impact looks neutral: https://llvm-compile-time-tracker.com/compare.php?from=0b7f01ad515d83f1f3144a44a1b0145187eff484&to=0246f42d60319147594948e073e86ebc55229b76&stat=instructions:u


https://github.com/llvm/llvm-project/pull/190347