if we enable binary logs, we should also enable max days for them

files/config/my.cnf.CentOS

@@ -1,6 +1,7 @@
 [mysqld]
 datadir=/var/lib/mysql/data
 log-bin=/var/lib/mysql/mysql-bin
+expire_logs_days=5
 socket=/var/lib/mysql/mysql.sock
 # Default to using old password format for compatibility with mysql 3.x
 # clients (those using the mysqlclient10 compatibility package).

files/config/my.cnf.Gentoo

@@ -53,6 +53,7 @@ log-error 					= /var/log/mysql/mysqld.err
 basedir 					= /usr
 datadir 					= /var/lib/mysql
 log-bin 					= /var/lib/mysql
+expire_logs_days            = 5
 skip-locking
 key_buffer 					= 16M
 max_allowed_packet 			= 1M