* bus/policy.c (bus_policy_create_client_policy): gracefully
	continue if the connection has no unix user - just don't apply
	any unix user dependent rules.

	* bus/config-parser.c: remove dbus-userdb.h usage

	* bus/bus.c: remove dbus-userdb.h usage

	* dbus/dbus-transport.c (_dbus_transport_get_is_authenticated):
	support Windows user function; also, fix the logic for checking
	auth as root in the default auth code (broken in the previous
	commit)

	* dbus/dbus-connection.c
	(dbus_connection_set_windows_user_function): new function
	(dbus_connection_get_windows_user): new function