value: micro-optimisation: avoid some unnecessary g_value_unset()
value: micro-optimisation: avoid some unnecessary g_value_unset()

We know there's nothing to do here and can save us the function
calls and GValueTable lookups.

jpxiong/gstreamer,cfoch/gstreamer,lovebug356/gstreamer,Lachann/gstreamer,drothlis/gstreamer,surround-io/gstreamer,lubosz/gstreamer,cablelabs/gstreamer,jpxiong/gstreamer,surround-io/gstreamer,krichter722/gstreamer,Lachann/gstreamer,centricular/gstreamer,jpakkane/gstreamer,drothlis/gstreamer,jpakkane/gstreamer,shelsonjava/gstreamer,justinjoy/gstreamer,StreamUtils/gstreamer,krieger-od/gstreamer,lubosz/gstreamer,cfoch/gstreamer,ensonic/gstreamer,drothlis/gstreamer,collects/gstreamer,collects/gstreamer,Lachann/gstreamer,jpakkane/gstreamer,StreamUtils/gstreamer,surround-io/gstreamer,lubosz/gstreamer,shelsonjava/gstreamer,cablelabs/gstreamer,shelsonjava/gstreamer,ensonic/gstreamer,surround-io/gstreamer,cablelabs/gstreamer,krichter722/gstreamer,lubosz/gstreamer,cfoch/gstreamer,drothlis/gstreamer,lovebug356/gstreamer,centricular/gstreamer,lubosz/gstreamer,collects/gstreamer,cfoch/gstreamer,krieger-od/gstreamer,StreamUtils/gstreamer,centricular/gstreamer,lovebug356/gstreamer,justinjoy/gstreamer,krieger-od/gstreamer,mparis/gstreamer,cablelabs/gstreamer,StreamUtils/gstreamer,cablelabs/gstreamer,justinjoy/gstreamer,centricular/gstreamer,krieger-od/gstreamer,jpakkane/gstreamer,centricular/gstreamer,mparis/gstreamer,ensonic/gstreamer,justinjoy/gstreamer,jpakkane/gstreamer,collects/gstreamer,cfoch/gstreamer,lovebug356/gstreamer,mparis/gstreamer,shelsonjava/gstreamer,mparis/gstreamer,jpxiong/gstreamer,mparis/gstreamer,drothlis/gstreamer,collects/gstreamer,krichter722/gstreamer,ensonic/gstreamer,krieger-od/gstreamer,Lachann/gstreamer,jpxiong/gstreamer,krichter722/gstreamer,StreamUtils/gstreamer,surround-io/gstreamer,lovebug356/gstreamer,jpxiong/gstreamer,ensonic/gstreamer,shelsonjava/gstreamer,justinjoy/gstreamer,krichter722/gstreamer,Lachann/gstreamer