[llvm] [CGP] Fold cmp+br+sub to usub+br on the overflow flag (PR #226496)

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github-actions[bot] wrote:

Failed to get test-suite diff from 83589c854329a8366672f9932ee27b422902038f...2ac313f9bc4bfe0393fd58700317f239875e25f1: https://github.com/llvm/llvm-project/actions/runs/36143309592

https://github.com/llvm/llvm-project/pull/226496