[llvm] [DA] Add tests for nsw doesn't hold on entire iteration space (NFC) (PR #162281)

[Ryotaro Kasuga via llvm-commits]

================

----------------
kasuga-fj wrote:

It looks to me that you still don't understand what `nsw` of addrecs means. `{a,+,c}<nsw>` does NOT say `a*i` doesn't overflow. It only says `(((c + a) + a) + ...)` doesn't overflow.

https://github.com/llvm/llvm-project/pull/162281