stdlib: Comment out NSArray: CollectionType conformance.
stdlib: Comment out NSArray: CollectionType conformance.

Dmitri notes that this should be API reviewed.

Swift SVN r28002

apple/swift-corelibs-foundation,apple/swift-corelibs-foundation,apple/swift-corelibs-foundation,apple/swift-corelibs-foundation,apple/swift-corelibs-foundation