Support AF_UNIX/AF_LOCAL sockets.

[wishstudio]

AF_UNIX/AF_LOCAL sockets is so different from normal sockets as they are completely unsupported in Windows. They are heavily used in Linux apps for interprocess communication.

The closest thing in Windows is a named pipe. We need to emulate socket function call behavior, mainly supporting blocking and non-blocking at the same time, support pooling, etc.

Maybe we need to clean up current socket code first, current code is a bit messy and not well commented.

[Globik]

Ipcs and family craches the flunux.exe. Systemctl does not work.