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

[David Sherwood via llvm-commits]

david-arm wrote:

Rebased this patch now that https://github.com/llvm/llvm-project/pull/128061 has landed. LLVM test suite seems fine, but I'll run some more tests to verify.

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