[clang] [CUDA][Win32] Add `fma(long double,..)` to math forward declares. (PR #73756)

[Evgeny Mankov via cfe-commits]

emankov wrote:

Hello, @fodinabor and @blinkfrog 

> the #ifdef _MSC_VER check may not be effective because _MSC_VER is specific to the MSVC compiler and is not defined when using Clang, even on Windows

Does it mean that this fix doesn't solve https://github.com/AdaptiveCpp/AdaptiveCpp/issues/1256? Or, is [blinkfrog](https://github.com/blinkfrog) saying above about yet other cases?


https://github.com/llvm/llvm-project/pull/73756