[llvm] [LV] Enable auto-vectorisation of loops with uncountable exits (PR #133099)

[via llvm-commits]

annamthomas wrote:

We've run our fuzzer downstream for couple of days with dereferencability checks disabled (to catch more early exit loops) and stress test the vectorizer with -force-vector-width. One miscompile was found, but that's not related to early-exit vectorization. 
LGTM from me.

https://github.com/llvm/llvm-project/pull/133099