Delete the copy constructor for llvm::yaml::Node (#83)
Delete the copy constructor for llvm::yaml::Node (#83)

The nodes keep a reference back to the original document, but the
document is streamed, not read all into memory at once, and the
position is part of the state. If nodes are ever copied, the document
position can end up being advanced more than once.

This did not reveal any problems in LLVM or Clang but caught a handful
over in Swift!

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@328345 91177308-0d34-0410-b5e6-96231b3b80d8
apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm,apple/swift-llvm