tracker-needle: Use accessor functions instead direct access
tracker-needle: Use accessor functions instead direct access

Fixes https://bugzilla.gnome.org/show_bug.cgi?id=640231

hoheinzollern/tracker,outofbits/tracker,outofbits/tracker,outofbits/tracker,hoheinzollern/tracker,hoheinzollern/tracker,hoheinzollern/tracker,hoheinzollern/tracker,outofbits/tracker,outofbits/tracker,hoheinzollern/tracker,outofbits/tracker,outofbits/tracker,hoheinzollern/tracker