Remove (incorrect) cast on gst_buffer_is_writable()
Remove (incorrect) cast on gst_buffer_is_writable()

Original commit message from CVS:
Remove (incorrect) cast on gst_buffer_is_writable()

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