Added a packet history object to the GDBRemoteCommunication class that is...

Added a packet history object to the GDBRemoteCommunication class that is always remembering the last 512 packets that were sent/received. These packets get dumped if logging gets enabled, or when the new expr lldb::DumpProcessGDBRemotePacketHistory (void *process, const char *log_file_path) global function is called.

llvm-svn: 154354