[llvm] [SPARC] Fix va_arg of long double on the 32-bit ABI (PR #228199)

[Imre Kaloz via llvm-commits]

kaloz wrote:

> Why do you need/want this functionality?
> 
> LLVM`s `va_arg`is very likely to miscompile code, because it does not have sufficient layout information. A frontend must, in effect, implement`va_arg` itself, much like clang and rustc already do. So I don't think it's really worth spending the lines to implement this logic without a specific use case.

This came from clang-built musl printing garbage for %Lf on 32-bit SPARC before #214981 landed. Now that clang and rustc both lower va_arg themselves, nothing depends on this anymore. Closing.

https://github.com/llvm/llvm-project/pull/228199