clock: assert about timestamp overflows
clock: assert about timestamp overflows

Assert when converting to timeval and timespec about overflows. This can happen
on platforms with 32bits long.

Fixes https://bugzilla.gnome.org/show_bug.cgi?id=678181

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