basesink: perform wait_preroll in a while loop
basesink: perform wait_preroll in a while loop

We need to continue calling wait_preroll() as long as the need_preroll variable
is true.

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