gstreamer: Move actual script to gstreamer repositories (#956)
gstreamer: Move actual script to gstreamer repositories (#956)

This will make it easier to add/extend/fix the fuzzing targets
and run them on gstreamer's CI system
robertswiecki/oss-fuzz,robertswiecki/oss-fuzz,robertswiecki/oss-fuzz,robertswiecki/oss-fuzz,robertswiecki/oss-fuzz,robertswiecki/oss-fuzz,robertswiecki/oss-fuzz,robertswiecki/oss-fuzz,robertswiecki/oss-fuzz,robertswiecki/oss-fuzz,robertswiecki/oss-fuzz