* dbus/dbus-spawn.c, dbus/dbus-spawn.h: Change dbus_spawn to
	return a "babysitter" object that is used to monitor the status of
	the spawned process and reap it when required.

	* test/test-segfault.c, test/test-exit.c,
	test/test-sleep-forever.c: binaries that do various lame things,
	used in the test suite.

	* dbus/dbus-sysdeps.c: kill _dbus_errno_to_string()