ecm: Work around build failure with Xcode 15

[mkoeppe]

Part of the fix for:

• Build failures with Xcode CLT 15.0: scipy (via meson), ecm #36342

📝 Checklist

• The title is concise, informative, and self-explanatory.
• The description explains in detail what this PR is about.
• I have linked a relevant issue or discussion.
• I have created tests covering the changes.
• I have updated the documentation accordingly.

⌛ Dependencies

[jhpalmieri]

I see the problem on an Intel mac, not an M2 mac. This fixes it for me.

[mkoeppe]

Thanks!

[github-actions]

Documentation preview for this PR (built with commit c22131f; changes) is ready! 🎉