Function gst_analytics_relation_meta_add_keypoint_mtd 

pub unsafe extern "C" fn gst_analytics_relation_meta_add_keypoint_mtd(
    instance: *mut GstAnalyticsRelationMeta,
    dimension: GstAnalyticsKeypointDimensions,
    x: c_int,
    y: c_int,
    z: c_int,
    visibility_flags: u8,
    confidence: c_float,
    keypoint_mtd: *mut GstAnalyticsKeypointMtd,
) -> gboolean