[llvm] [LV] Avoid redundant SCEVChecks on active lane mask (PR #171605)

[Ramkumar Ramachandra via llvm-commits]

artagnon wrote:

> Why don't we need the pointer overflow checks when we have an active lane mask?

MemChecks are still needed, and this patch doesn't change that?

https://github.com/llvm/llvm-project/pull/171605