[APINotes] Fix build error with creating 'AvailabilityAttr', after upstream changes.
[APINotes] Fix build error with creating 'AvailabilityAttr', after upstream changes.

apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang