message: core: fix GCC 8 warning
  The destination needs to be 1 char longer than the num of chars that are
  copied in order to make sure the resulting string at the destination is
  null-terminated.
diff: @@ -108,7 +108,7 @@ void MAVLinkParameters::do_work()
  _state = State::SET_PARAM_BUSY;
  char param_id[PARAM_ID_LEN] = {};
  - STRNCPY(param_id, set_param_work->param_name.c_str(), sizeof(param_id));
  + STRNCPY(param_id, set_param_work->param_name.c_str(), sizeof(param_id) - 1);
  mavlink_message_t message = {};
  if (set_param_work->extended) {
  @@ -165,7 +165,7 @@ void MAVLinkParameters::do_work()
  _state = State::GET_PARAM_BUSY;
  char param_id[PARAM_ID_LEN] = {};
  - STRNCPY(param_id, get_param_work->param_name.c_str(), sizeof(param_id));
  + STRNCPY(param_id, get_param_work->param_name.c_str(), sizeof(param_id) - 1);
  // LogDebug() << "now getting: " << get_param_work->param_name;
  