* dbus/dbus-auth.c: adapt to keyring changes

	* dbus/dbus-keyring.c: change to avoid using user ID and home
	directory directly; instead use a
	keyring-location-from-credentials function in dbus-sysdeps

	* fix to use _dbus_append_user_from_current_process() instead of
	_dbus_username_from_current_process() or _dbus_append_desired_identity().