[llvm] [Intrinsics][AArch64] Add intrinsic to mask off aliasing vector lanes (PR #117007)

[David Green via llvm-commits]

https://github.com/davemgreen approved this pull request.

Thanks, I'm not sure about these shouldExpand functions but I can see that is used elsewhere, and in general this LGTM. It would be good to use these to generate runtime alias checks using the last lane. 

https://github.com/llvm/llvm-project/pull/117007