[clang] [llvm] [AVR] Fix Avr indvar detection and strength reduction (missed optimization) (PR #152028)

[Tom Vijlbrief via llvm-commits]

tomtor wrote:

I just checked the latest Rust nightly. It produces now also the longer version! So it is a Rust regression. This PR is fine. 

https://github.com/llvm/llvm-project/pull/152028