[portmidi] Changes to allow compiling osx with osxcross

[nonameentername]

• [x] Changes comply with the maintainer guide.
• [ ] SHA512s are updated for each updated download.
• [ ] The "supports" clause reflects platforms that may be fixed by this new version.
• [ ] Any fixed CI baseline entries are removed from that file.
• [ ] Any patches that are no longer applied are deleted from the port's directory.
• [x] The version database is fixed by rerunning ./vcpkg x-add-version --all and committing the result.
• [x] Only one version is added to each modified port's versions file.

[data-queue]

Can you explain what problem this fixes?