[Attributor][NFX] Pre-commit test case exposing a problem

The test case is the IR of:

```
  void func(float * restrict a, float *b, int N) {
    N = 199;
    #pragma omp parallel for
    for (int i = 1; i < N; i++)
      a[i] = b[i] + 1.0;
  }
```