event: add manual exit handler

[KevlarKanou]

nvboard_manual_exit_handler() is used to perform certain actions in the testbench when the simulation is manually terminated.

[sashimi-yzh]

Would you please provide any actions for example which should be performed in the exit handler?

[KevlarKanou]

Would you please provide any actions for example which should be performed in the exit handler?

eg: exporting logs when manually stopping an endless simulation

void nvboard_manual_exit_handler() {
  std::fwrite(..., fp);
  std::fclose(fp);
}

[sashimi-yzh]

I think this does not belong to the responsibility of NVBoard. Therefore we are not going to provide this API. You can use atexit() instead, or modify code directly.