don't use deprecated options in the installed config files

debian/additions/mariadb.cnf

@@ -3,7 +3,7 @@
 
 [client]
 # Default is Latin1, if you need UTF-8 set this (also in server section)
-#default-character-set  = utf8 
+#character-set-server  = utf8 
 
 [mysqld]
 #
@@ -11,7 +11,7 @@
 # 
 # Default is Latin1, if you need UTF-8 set all this (also in client section)
 #
-#default-character-set  = utf8 
-#default-collation      = utf8_general_ci 
+#character-set-server  = utf8 
+#collation-server      = utf8_general_ci 
 #character_set_server   = utf8 
 #collation_server       = utf8_general_ci