[llvm] DAG: Handle lowering unordered compare with inf (PR #100378)

[Matt Arsenault via llvm-commits]

arsenm wrote:

### Merge activity

* **Sep 5, 11:48 AM EDT**: @arsenm started a stack merge that includes this pull request via [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/100378).


https://github.com/llvm/llvm-project/pull/100378