allocator: fix memory leak in _fallback_mem_copy
allocator: fix memory leak in _fallback_mem_copy

https://bugzilla.gnome.org/show_bug.cgi?id=686658

shelsonjava/gstreamer,cablelabs/gstreamer,surround-io/gstreamer,lubosz/gstreamer,justinjoy/gstreamer,centricular/gstreamer,StreamUtils/gstreamer,jpakkane/gstreamer,shelsonjava/gstreamer,collects/gstreamer,cablelabs/gstreamer,cfoch/gstreamer,surround-io/gstreamer,jpxiong/gstreamer,jpxiong/gstreamer,surround-io/gstreamer,lovebug356/gstreamer,ensonic/gstreamer,surround-io/gstreamer,cablelabs/gstreamer,shelsonjava/gstreamer,cfoch/gstreamer,cfoch/gstreamer,jpakkane/gstreamer,jpakkane/gstreamer,mparis/gstreamer,Lachann/gstreamer,ensonic/gstreamer,justinjoy/gstreamer,cablelabs/gstreamer,lubosz/gstreamer,StreamUtils/gstreamer,collects/gstreamer,ensonic/gstreamer,krichter722/gstreamer,cablelabs/gstreamer,centricular/gstreamer,ensonic/gstreamer,krichter722/gstreamer,mparis/gstreamer,lubosz/gstreamer,ensonic/gstreamer,shelsonjava/gstreamer,mparis/gstreamer,surround-io/gstreamer,mparis/gstreamer,collects/gstreamer,jpakkane/gstreamer,justinjoy/gstreamer,krichter722/gstreamer,lubosz/gstreamer,krieger-od/gstreamer,cfoch/gstreamer,jpakkane/gstreamer,mparis/gstreamer,centricular/gstreamer,krichter722/gstreamer,krieger-od/gstreamer,Lachann/gstreamer,StreamUtils/gstreamer,jpxiong/gstreamer,centricular/gstreamer,Lachann/gstreamer,lovebug356/gstreamer,lovebug356/gstreamer,krieger-od/gstreamer,justinjoy/gstreamer,collects/gstreamer,jpxiong/gstreamer,lubosz/gstreamer,krieger-od/gstreamer,StreamUtils/gstreamer,collects/gstreamer,lovebug356/gstreamer,krieger-od/gstreamer,cfoch/gstreamer,Lachann/gstreamer,centricular/gstreamer,shelsonjava/gstreamer,StreamUtils/gstreamer,justinjoy/gstreamer,krichter722/gstreamer,lovebug356/gstreamer,Lachann/gstreamer,jpxiong/gstreamer