* bus/dispatch.c (bus_dispatch_test): do test using debug-pipe
	transport, tests more of the real codepath. Set up clients
	with bus_setup_debug_client.

	* bus/test.c (bus_setup_debug_client): function to set up debug
	"clients" on the main loop

	* dbus/dbus-transport.c (_dbus_transport_open): add debug-pipe
	support

	* dbus/dbus-server.c (dbus_server_listen): add debug-pipe
	server type

	* dbus/dbus-server-debug.c: support a debug server based on pipes

	* dbus/dbus-sysdeps.c (_dbus_full_duplex_pipe): new function
	(_dbus_close): new function

	* configure.in: check for socketpair