isMacosCppModule function
Returns true when the spec file uses direct C++ specifically for macOS.
Use this instead of isAppleCppModule when deciding whether the macOS Swift
Plugin.swift needs a Registry.register() call — a mixed module with
ios: cpp, macos: swift still needs the macOS Swift registration.
Implementation
bool isMacosCppModule(File specFile) =>
PlatformTargetAnalyzer.fromSpec(specFile).supportsMacosCpp;