testclock: remove unused variable
testclock: remove unused variable

Fixes compiler warning.

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