[clang] [llvm] [openmp] [Clang][OpenMP] Implement Loop splitting `#pragma omp split` directive (PR #183261)

[Amit Tiwari via llvm-commits]

amitamd7 wrote:

> Additional end2end test ideas:
> 
> * `counts(v,omp_fill)`, `counts(omp_fill)` (non-contant `v`)
> * loop with negative increment: `for (int i = n; i >= 0; --i)`
> * loop with non-constant increment: `for (int i = 0; i < n; i+=c)`
> 
> I think at least the first should be covered

Added: nonconstant_incr.c, negative_incr.c & nonconstant_count.c

https://github.com/llvm/llvm-project/pull/183261