[llvm] [LoopVectorize] Perform loop versioning for some early exit loops (PR #120603)

[David Sherwood via llvm-commits]

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

For now, I've changed it so that loop versioning is turned off by default. When the user is confident that MTE compatibility is not required they can enable it manually. In future, it would be good to revisit this because even with MTE we can still vectorise with max vector widths of 16 bytes, and memory tagging is currently only supported in LLVM for Android targets anyway.

https://github.com/llvm/llvm-project/pull/120603