System information (version)

• OpenCV => master
• Operating System / Platform => iOS
• Compiler => XCode

Detailed description

Build fails with:
Fatal error: Unsupported CXCursorKind: UnionDecl: file /Users/johnf/project/jazzy/SourceKitten/Source/SourceKittenFramework/ObjCDeclarationKind.swift

Steps to reproduce

Install jazzy (gem install jazzy)
Run iOS build (./opencv/platforms/ios/build_framework.py iosbuild)

Issue submission checklist

• I report the issue, it's not a question
• I updated to latest OpenCV version and the issue is still there

I have a PR ready for this