[polly] [Polly] Retain vectorization for fallback loop when RTC is false (PR #165525)

[Michael Kruse via llvm-commits]

https://github.com/Meinersbur commented:

Title: 

> Retain vectorization for fallback loop when RTC is false

To disambiguate with "when RTC evaluates to false", maybe RTC is a [unsatisfiable](https://en.wikipedia.org/wiki/Satisfiability)". Ideally, we would not get to code generation at all if the SCoP's context is a contradition (so the only situation where this happens is when code generation itself fails), but could not find such check.

https://github.com/llvm/llvm-project/pull/165525