collectpads: avoid doing subbuffers when we can
collectpads: avoid doing subbuffers when we can

In some cases we can avoid allocating a subbuffer and instead simply ref
the buffer. Callers should perform _make_metadata_writable() in all
cases now.

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