asio: use the protocol reported by the endpoint instead of ipv4.
asio: use the protocol reported by the endpoint instead of ipv4.

On some computers, localhost resolves as ::1 now.

	* include/libport/asio.hxx (listenUDP): Pass the protocol of the
	endpoint to open.

aldebaran/libport,aldebaran/libport,aldebaran/libport,aldebaran/libport,aldebaran/libport