Added 'sock_error' value for different platforms

1. For WinRT __*SOCKET__ is "Windows::Networking::Sockets::DatagramSocket ^" and created with WinRTCreateStreamSocket()
2. For Win32 if error occur socket() return -1 if and __*SOCKET__ is UINT_PTR. winsock2.h have define "INVALIDE_SOCKET (SOCKET)(~0)"
3. Unix __*SOCKET__ is int and if error occur return -1.