[libclc] [libclc] Move fma to the CLC library (PR #126052)

[Romaric Jodin via cfe-commits]

rjodinchr wrote:

> FYI @rjodinchr this breaks downstream clspv testing.
> 
> ```
> # | declare !kernel_arg_name !7 float @llvm.fma.f32(float, float, float) #2
> # | Unsupported llvm intrinsic
> # | UNREACHABLE executed at /clspv/lib/SPIRVProducerPass.cpp:2390!
> ```
> 
> I was wondering if clspv should be translating `llvm.fma` to `OpExtInst fma` as `llvm-spirv` does.

I guess it would just be a question of adding `llvm.fma` here: https://github.com/google/clspv/blob/0878df110af85e84d0c336e6571767278ad5eec8/lib/Builtins.cpp#L703

https://github.com/llvm/llvm-project/pull/126052