[llvm-branch-commits] [SimplifyLibCalls] Fix profiles in optimizeFFS (PR #229842)

[Aiden Grossman via llvm-branch-commits]

https://github.com/boomanaiden154 created https://github.com/llvm/llvm-project/pull/229842

We were creating a select with a condition that compares the input value
to the null value for that type. Mark that condition as being unlikely
as that should hold for most callsites in most applications.