[llvm] [llvm][SimplifyLibCalls] Add option 'AllowMemcmpToBcmpTransform' (PR #82304)

[Ralf Jung via llvm-commits]

RalfJung wrote:

I can't help with reviewing unfortunately as I'm not familiar with the codebase, but I support having such a flag. :)

https://github.com/llvm/llvm-project/pull/82304