[llvm] [LV] Don't ignore invariant stores when costing (PR #158682)

[Ramkumar Ramachandra via llvm-commits]

artagnon wrote:

> Looks like this needed a rebase before merging. Woul be good to update to latest main before merging and see if everything still passes

Sorry, my bad! Currently building opt to fixup test.

https://github.com/llvm/llvm-project/pull/158682