flacparse: do not leak uid after parsing TOC event
flacparse: do not leak uid after parsing TOC event

https://bugzilla.gnome.org/show_bug.cgi?id=736739

wkatsak/gst-plugins-good,vatavuserban/gst-plugins-good,ndufresne/gst-plugins-good,wkatsak/gst-plugins-good,surround-io/gst-plugins-good,ndufresne/gst-plugins-good,vatavuserban/gst-plugins-good,jpakkane/gstreamer-plugins-good,surround-io/gst-plugins-good,jpakkane/gstreamer-plugins-good,jpakkane/gstreamer-plugins-good,wkatsak/gst-plugins-good,vatavuserban/gst-plugins-good,jpakkane/gstreamer-plugins-good,vatavuserban/gst-plugins-good,surround-io/gst-plugins-good,wkatsak/gst-plugins-good,surround-io/gst-plugins-good,ndufresne/gst-plugins-good,ndufresne/gst-plugins-good