[llvm-branch-commits] [llvm] DAG: Check if is_fpclass is custom, instead of isLegalOrCustom (PR #105577)

[Matt Arsenault via llvm-branch-commits]

arsenm wrote:

### Merge activity

* **Aug 29, 5:54 AM EDT**: @arsenm started a stack merge that includes this pull request via [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/105577).


https://github.com/llvm/llvm-project/pull/105577