tracker: Adapt to new Vala version
tracker: Adapt to new Vala version

Pelagicore/Media-Manager-Rygel-patched,GNOME/rygel,GNOME/rygel,Pelagicore/Media-Manager-Rygel-patched,jku/rygel,Tarnyko/rygel,Tarnyko/rygel,Pelagicore/Media-Manager-Rygel-patched,GNOME/rygel,luisbg/rygel,jku/rygel