tracker: Declare sync call as such
tracker: Declare sync call as such

We were calling a D-Bus method synchronously while it was declared
'async' which resulted in us not able to catch errors from it.

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