Exit when mysql is absent

[camlafit]

Hi

For different reason, mysql could be down during php7-fpm execution. In this case, all pool are deleted and break all sites hosted.

We must check mysql state and ran script only we are sure mysql state

[camlafit]

We can have different use case as :

• MysqlPDO instanceSQLSTATE[08004] [1040] Too many connections
• MysqlPDO instanceSQLSTATE[HY000] [2002] Connection reset by peer
• MysqlPDO instanceSQLSTATE[HY000] [2002] Connection refused
• PHP Warning: PDO::query(): MySQL server has gone away