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

[Fraser Cormack via cfe-commits]

frasercrmck 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.

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