[llvm] Enable logf128 constant folding for hosts with 128bit long double (PR #104929)

[NAKAMURA Takumi via llvm-commits]

chapuni wrote:

@MDevereau I wonder this causes different behavior, for generated binaries by clang, between !HAS_LOGF128 and HAS_LOGF128.

My case: I am making my builders check artifacts between "aarch64 object files built by aarch64-clang" and "aarch64 object files built by x86_64-clang for targeting aarch64". This triggers the incompatibility. Investigating.

I hope LLVM_HAS_LOGF128 to remain optional, if HAS_LOGF128 would introduce the different behavior.
I'd be really happy if you could revert this for now.

https://github.com/llvm/llvm-project/pull/104929