[llvm] ConstantFold logl calls (PR #94944)

[David Green via llvm-commits]

davemgreen wrote:

> Done, I've removed the zero and negative checks as well to keep it consistent with the logf.128 behaviour.

It needs to produce the same errno and fpexeption values. I can see that the intrinsic remains, but would recommend making it work the same as floats: https://godbolt.org/z/T5x7foe4Y

https://github.com/llvm/llvm-project/pull/94944