video-sink: Add NV12 shader support
video-sink: Add NV12 shader support

Based on patch from Lionel Landwerlin.

https://bugzilla.gnome.org/show_bug.cgi?id=712832

lubosz/clutter-gst,lubosz/clutter-gst,ystreet/clutter-gst,ystreet/clutter-gst,lubosz/clutter-gst,ystreet/clutter-gst,ystreet/clutter-gst