[llvm] [X86][CodeGen] Restrict F128 lowering to GNU environment (PR #81664)

[Arthur Eubanks via llvm-commits]

aeubanks wrote:

https://godbolt.org/z/fhjEd3G4v shows that x64 Android uses f128 with `*l` builtins

https://github.com/llvm/llvm-project/pull/81664