[Feature Request] Allow threshold Daemon to shutdown if mysql proccess is down

[bmfmancini]

One useful feature to have for the threshold daemon is to have it shutdown when it detects the MySQL service is down

The below logs will bombard the cacti log which can grow significantly until the issue is fixed the below is a sample of these events

2021-03-13 22:37:11 - CMDPHP SQL Backtrace:  (/plugins/thold/thold_daemon.php[269]:db_fetch_assoc(), /lib/database.php[476]:db_fetch_assoc_prepared(), /lib/database.php[490]:db_execute_prepared())
2021-03-13 22:37:11 - CMDPHP ERROR: A DB Row Failed!, Error: MySQL server has gone away
2021-03-13 22:37:11 - CMDPHP SQL Backtrace:  (/plugins/thold/thold_daemon.php[258]:set_config_option(), /lib/functions.php[344]:db_execute_prepared())
2021-03-13 22:37:11 - CMDPHP ERROR: A DB Exec Failed!, Error: MySQL server has gone away
2021-03-13 22:37:11 - CMDPHP SQL Backtrace:  (/plugins/thold/thold_daemon.php[257]:thold_db_connection(), /plugins/thold/thold_daemon.php[343]:db_fetch_cell(), /lib/database.php[386]:db_fetch_cell_prepared(), /lib/database.php[402]:db_execute_prepared())
2021-03-13 22:37:11 - CMDPHP ERROR: A DB Cell Failed!, Error: MySQL server has gone away
2021-03-13 22:37:11 - CMDPHP SQL Backtrace:  (/plugins/thold/thold_daemon.php[290]:db_fetch_cell(), /lib/database.php[386]:db_fetch_cell_prepared(), /lib/database.php[402]:db_execute_prepared())
2021-03-13 22:37:11 - CMDPHP ERROR: A DB Cell Failed!, Error: MySQL server has gone away
2021-03-13 22:37:11 - CMDPHP SQL Backtrace:  (/plugins/thold/thold_daemon.php[269]:db_fetch_assoc(), /lib/database.php[476]:db_fetch_assoc_prepared(), /lib/database.php[490]:db_execute_prepared())
2021-03-13 22:37:11 - CMDPHP ERROR: A DB Row Failed!, Error: MySQL server has gone away