[clang] [Clang] Force expressions with UO_Not to not be non-negative (PR #126846)

[Yutong Zhu via cfe-commits]

YutongZhuu wrote:

> Can you update the first comment on this PR to reflect what you want to be in the commit message? I notice that it doesn't describe what you're doing with negation yet. Thanks!

Hello, can you merge this or delete the review request I sent? This was due to an unsuccessful git rebase :(
Sorry about that.

https://github.com/llvm/llvm-project/pull/126846