baseparse: minor fixes and enhancements
baseparse: minor fixes and enhancements

Arrange for upstream as well as downstream flushing when seeking.
Also determine upstream size as well as seekability.  Adjust some comments
to reality and employ debug statement in proper order.

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