[llvm] SimplifyLibCalls: Don't require ldexp to emit intrinsic in exp2 combine (PR #92707)

[Eli Friedman via llvm-commits]

efriedma-quic wrote:

> > On Windows specifically, we have ldexp; the issue is just that we don't have ldexpf.
> 
> Can we handle this by just promoting float to double in codegen?

Yes, that's fine; the Windows math.h does exactly the same thing.

https://github.com/llvm/llvm-project/pull/92707