[llvm] [ConstantFolding] Add flag to disable call folding (PR #140270)

[Artem Belevich via llvm-commits]

Artem-B wrote:

@LewisCrawford Thank you. I appreciate your thoughtful response. With the intended scope of the patch as a debug-only knob, a most of my concerns and handwaving are moot, and applying it to functions with FP results or arguments is good enough.

We can revisit more granular selection if/when we actually need it.

https://github.com/llvm/llvm-project/pull/140270