[polly] [Polly] Fix codegen assertions to account for DefinedBehaviorContext (PR #209188)

[Karthika Devi C via llvm-commits]

kartcq wrote:

> Yes, that's the usual practice. Try to simplify as much as possible (e.g. removing `target triple = "aarch64-unknown-linux-gnu"`)
> 
> https://llvm.org/docs/TestingGuide.html#best-practices-for-regression-tests

Sure. Added test case.
Thanks.

https://github.com/llvm/llvm-project/pull/209188