Function gstreamer_video_sys::gst_video_decoder_request_sync_point

pub unsafe extern "C" fn gst_video_decoder_request_sync_point(
    dec: *mut GstVideoDecoder, 
    frame: *mut GstVideoCodecFrame, 
    flags: GstVideoDecoderRequestSyncPointFlags
)

This is supported on crate feature v1_20 only.