stdlib: note that the CFXyzCreateCopy bugs were fixed
stdlib: note that the CFXyzCreateCopy bugs were fixed

Since Swift deploys back to OS X 10.9 and iOS 7.0, we should continue to
use the API that works everywhere.

Swift SVN r29057

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