DBusInterfaceInfo.cacheBuild

Builds a lookup-cache to speed up gio.dbus_interface_info.DBusInterfaceInfo.lookupMethod, gio.dbus_interface_info.DBusInterfaceInfo.lookupSignal and gio.dbus_interface_info.DBusInterfaceInfo.lookupProperty.

If this has already been called with info, the existing cache is used and its use count is increased.

Note that info cannot be modified until gio.dbus_interface_info.DBusInterfaceInfo.cacheRelease is called.