Make the AppSrc example work on big endian architectures too
Make the AppSrc example work on big endian architectures too

Cairo's ARGB32 format is defined to be native endianness, i.e.
we have to use GST_VIDEO_FORMAT_ARGB or _BGRA depending on
endianness.

freedesktop-unofficial-mirror/gstreamer__gstreamer-sharp,GStreamer/gstreamer-sharp,Forage/gstreamer-sharp,gstreamer-sharp/gstreamer-sharp,GStreamer/gstreamer-sharp,freedesktop-unofficial-mirror/gstreamer__gstreamer-sharp,freedesktop-unofficial-mirror/gstreamer__gstreamer-sharp,Forage/gstreamer-sharp,gstreamer-sharp/gstreamer-sharp,Forage/gstreamer-sharp,GStreamer/gstreamer-sharp,gstreamer-sharp/gstreamer-sharp,Forage/gstreamer-sharp