add Dockerfile for clang

Create: Dockerfile, Test.cpp

Create: Dockerfile, async2.cpp

Create: async2.cpp, async2.slnx

Create: async1.cpp, async1.slnx

Create: CMakeLists.txt, TcpClient.cpp, TcpClient.h, TcpClientMain.cpp, TcpMultiServer.cpp, TcpMultiServer.h, TcpMultiServerMain.cpp, TcpServer.cpp, TcpServer.h, TcpServerMain.cpp

Create: TcpClient.cpp, TcpClient.h, TcpClientMain.cpp, TcpServer.cpp, TcpServer.h, TcpServerMain.cpp, CMakeLists.txt