[llvm] MSP430: Add tests for fcmp (PR #142706)

[Matt Arsenault via llvm-commits]

arsenm wrote:

### Merge activity

* **Jun 11, 12:00 PM UTC**: A user started a stack merge that includes this pull request via [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/142706).


https://github.com/llvm/llvm-project/pull/142706