GDBusProxy: Fix a memory leak during initialization
GDBusProxy: Fix a memory leak during initialization

https://bugzilla.gnome.org/show_bug.cgi?id=758641

johne53/MB3Glib,johne53/MB3Glib,johne53/MB3Glib,johne53/MB3Glib,johne53/MB3Glib,johne53/MB3Glib