Function t42_decode_set_row_write_handler 

pub unsafe extern "C" fn t42_decode_set_row_write_handler(
    s: *mut t42_decode_state_t,
    handler: t4_row_write_handler_t,
    user_data: *mut c_void,
) -> c_int

\brief Set the row handler routine. \param s The T.42 context. \param handler A callback routine to handle decoded image rows. \param user_data An opaque pointer passed to handler. \return 0 for OK.