[compiler-rt] [compiler-rt] Disable tests for unavailable builtins (PR #158664)

[Saleem Abdulrasool via llvm-commits]

https://github.com/compnerd commented:

I think that we can get away with a simpler:

```
#if defined(CRT_HAS_TF_MODE)
```
and
```
#if defined(CRT_HAS_128BIT) && defined(CRT_HAS_F128)
```
and entirely drop the architecture checks. That simplifies the conditions and still serves the need. It also avoids this type of issue cropping up elsewhere.

https://github.com/llvm/llvm-project/pull/158664