pub unsafe extern "C" fn coap_add_optlist_pdu(
pdu: *mut coap_pdu_t,
optlist_chain: *mut *mut coap_optlist_t,
) -> c_int
pub unsafe extern "C" fn coap_add_optlist_pdu(
pdu: *mut coap_pdu_t,
optlist_chain: *mut *mut coap_optlist_t,
) -> c_int