[clang] [llvm] [clang][CodeGen] Generate follow-up metadata for loops in correct format (PR #131985)

[Ryotaro Kasuga via cfe-commits]

kasuga-fj wrote:

> For this reason OpenMP 5.1 added new pragma:
> 
> ```c
> #pragma omp simd reduction(+:v0)
> #pragma omp unroll partial(4)
> ```

FWIW, I tried it and the following error occurred.

```
<source>:10:1: error: OpenMP constructs may not be nested inside a simd region except for ordered simd, simd, scan, or atomic directive
   10 | #pragma omp unroll partial(4)
      | ^
```

https://github.com/llvm/llvm-project/pull/131985