[clang] [clang] Always pass fp128 arguments indirectly on Windows (PR #115052)

[Nikita Popov via cfe-commits]

nikic wrote:

@tgross35 Libcalls are handled by the backend. I think you'd have to modify the CC_X86_Win64_C / RetCC_X86_Win64_C calling conventions in https://github.com/llvm/llvm-project/blob/main/llvm/lib/Target/X86/X86CallingConv.td for that.

https://github.com/llvm/llvm-project/pull/115052