* dtable.cc (dtable::dup2): Store fd for fhandler_socket.

	* dtable.cc (dtable::dup2): Store fd for fhandler_socket.
	* fhandler.h (fhandler_base::set_fd): New virtual method.
	(fhandler_base::get_fd): Ditto.
	(fhandler_socket::set_fd): Ditto.
	(fhandler_socket::get_fd): Ditto.
	* fhandler_socket.cc (fhandler_socket::read): Call cygwin_recv instead
	of native Winsock recv.
	(fhandler_socket::write): Call cygwin_send instead of native Winsock
	send.
	* net.cc (fdsock): Store fd in fhandler_socket.