gstcheck: fix some silly list iteration code
gstcheck: fix some silly list iteration code

g_list_length() is not the best way to check if a list is empty or not.

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