Add _with_closures alternative functions for those in GDBus that

accept more than one callback.

g_bus_own_name_with_closures
g_bus_own_name_on_connection_with_closures
g_bus_watch_name_with_closures
g_bus_watch_name_on_connection_with_closures
g_bus_watch_proxy_with_closures
g_bus_watch_proxy_on_connection_with_closures

https://bugzilla.gnome.org/show_bug.cgi?id=621092