GtkSearchEngineTracker: port to tracker 0.12
GtkSearchEngineTracker: port to tracker 0.12

We simply use the Tracker DBus api here, caching and direct
access that come with libtracker-sparql are probably not needed
here. Based on a patch by Martyn Russell.

https://bugzilla.gnome.org/show_bug.cgi?id=658272

Unity-Technologies/gtk,johne53/MB3Gtk-2,johne53/MB3Gtk-2,johne53/MB3Gtk-2,johne53/MB3Gtk-2,Unity-Technologies/gtk,Distrotech/gtk,Unity-Technologies/gtk,Distrotech/gtk,Distrotech/gtk,Unity-Technologies/gtk,Distrotech/gtk,Distrotech/gtk,Unity-Technologies/gtk,johne53/MB3Gtk-2