benchmarks: capsnego: add --loops command line option
benchmarks: capsnego: add --loops command line option

And default to 50 loops.

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