parse: Add comment about why we disable the "tracing"
parse: Add comment about why we disable the "tracing"

It did not print anything useful before anyway, everything
was commented out.

Also remove some unneeded struct members.

cablelabs/gstreamer,centricular/gstreamer,jpakkane/gstreamer,Lachann/gstreamer,shelsonjava/gstreamer,mparis/gstreamer,jpxiong/gstreamer,Lachann/gstreamer,jpakkane/gstreamer,mparis/gstreamer,krichter722/gstreamer,ensonic/gstreamer,krichter722/gstreamer,Lachann/gstreamer,cfoch/gstreamer,Lachann/gstreamer,StreamUtils/gstreamer,cfoch/gstreamer,surround-io/gstreamer,cfoch/gstreamer,Lachann/gstreamer,jpxiong/gstreamer,centricular/gstreamer,centricular/gstreamer,surround-io/gstreamer,krichter722/gstreamer,jpxiong/gstreamer,jpxiong/gstreamer,jpakkane/gstreamer,cfoch/gstreamer,ensonic/gstreamer,StreamUtils/gstreamer,centricular/gstreamer,mparis/gstreamer,shelsonjava/gstreamer,ensonic/gstreamer,StreamUtils/gstreamer,ensonic/gstreamer,mparis/gstreamer,jpakkane/gstreamer,cablelabs/gstreamer,shelsonjava/gstreamer,shelsonjava/gstreamer,ensonic/gstreamer,cablelabs/gstreamer,surround-io/gstreamer,mparis/gstreamer,shelsonjava/gstreamer,centricular/gstreamer,krichter722/gstreamer,StreamUtils/gstreamer,jpxiong/gstreamer,StreamUtils/gstreamer,krichter722/gstreamer,surround-io/gstreamer,cablelabs/gstreamer,cablelabs/gstreamer,jpakkane/gstreamer,surround-io/gstreamer,cfoch/gstreamer