Completed more work on the KDP darwin kernel debugging Process plug-in.

Implemented connect, disconnect, reattach, version, and hostinfo.

Modified the ConnectionFileDescriptor class to be able to handle UDP. 

Added a new Stream subclass called StreamBuffer that is backed by a
llvm::SmallVector for better efficiency.

Modified the DataExtractor class to have a static function that can
dump hex bytes into a stream. This is currently being used to dump incoming
binary packet data in the KDP plug-in.

llvm-svn: 135338