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

[Luke Lau via llvm-commits]

lukel97 wrote:

> I think the SCEVChecks amount to checking that the IV update won't overflow, which should be addressed by ALM?

Only TailFoldingStyle::DataAndControlFlowWithoutRuntimeCheck can skip the overflow checks, I think we'll still need them for the other TailFoldingStyles. 

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