[llvm] [LoopVectorize] Add support for vectorisation of more early exit loops (PR #88385)

[Graham Hunter via llvm-commits]

https://github.com/huntergr-arm commented:

Starting to review the core representation in VPlan now; in the meantime, I think we can cut down on overall diff size by removing the ScalarEvolution changes.

https://github.com/llvm/llvm-project/pull/88385