[libclc] [libclc] Add (fast) normalize to CLC; add half overloads (PR #139759)

[Fraser Cormack via cfe-commits]

frasercrmck wrote:

> > I wasn't sure if this was necessary so this commit replaces the vector2 versions of the constants with the vector3/vector4 ones. The OpenCL-CTS seems okay with it. If this is incorrect then it's not very difficult to split them back out again.
> 
> Does it pass with -cl-denorms-are-zero and with denormal support?

The OpenCL-CTS doesn't actually test the geometrics builtins with that option - that's just for bruteforce.

It passes on an OpenCL implementation which advertises support for single-precision denormals, yes.

https://github.com/llvm/llvm-project/pull/139759