Function gst_ element_ add_ pad 
Source pub unsafe extern "C" fn gst_element_add_pad(
    element: *mut GstElement,
    pad: *mut GstPad,
) -> gbooleanpub unsafe extern "C" fn gst_element_add_pad(
    element: *mut GstElement,
    pad: *mut GstPad,
) -> gboolean