at version 4.0 or above, we need to create one 'config.inc.php' or rename the 'config.sample.inc.php' to 'config.inc.php';
In my case, I also work with one mysql server for each environment (dev and production):
/* others code*/
$whoIam = gethostname();
switch($whoIam) {
case 'devHost':
$cfg['Servers'][$i]['host'] = 'localhost';
break;
case 'MasterServer':
$cfg['Servers'][$i]['host'] = 'masterMysqlServer';
break;
} /* others code*/