[flang] [llvm] [flang][openacc] parse and ignore non-standard shortloop clause (PR #106564)

[Razvan Lupusoru via llvm-commits]

https://github.com/razvanlupusoru approved this pull request.

Excellent! This is great to not have compiler choke on seeing this clause :)

https://github.com/llvm/llvm-project/pull/106564