[llvm] [DA] Require 'nsw' for AddRecs in the WeakCrossing SIV test (PR #185041)

[Sjoerd Meijer via llvm-commits]

sjoerdmeijer wrote:

This looks like good little fix to me, so LGTM. 

I will be offline for 2 weeks and won't be able to participate in discussions, so will leave the final sign off up to @kasuga-fj.

https://github.com/llvm/llvm-project/pull/185041