Update: Socket parameters, rename f_socket_bind_file() to f_socket_bind_local(),...

Update: Socket parameters, rename f_socket_bind_file() to f_socket_bind_local(), and return F_local_not when UNIX socket is required.

Make the f_socket_t passed to the f_socket_bind() and f_socket_bind_file() a pointer constant.

Use the f_socket_bind_local() rather than f_socket_bind_file() to better communicate that this is a local (UNIX) socket.
The f_socket_bind_local() requires the socket to be a local (UNIX) socket, so return F_local_not (with error bit) if it is not a local (UNIX) socket.