[libclc] [libclc] Refine __clc_fp*_subnormals_supported and __clc_flush_denormal_if_not_supported (PR #157633)

[Wenju He via cfe-commits]

wenju-he wrote:

> Is the build using `-Xclang -fdenormal-fp-math-f32=dynamic` already? If not it should do that globally

Thanks, I forgot that part. Done in https://github.com/llvm/llvm-project/pull/157633/commits/4608f77d4bc81ec584e5c3c2d19b446ffc919a2f


https://github.com/llvm/llvm-project/pull/157633