remove unnecessary method overrides in DB2

lib/Doctrine/DBAL/Platforms/DB2Platform.php

@@ -235,30 +235,6 @@ class DB2Platform extends AbstractPlatform
         return 'TRUNCATE ' . $tableName . ' IMMEDIATE';
     }
 
-    /**
-     * {@inheritDoc}
-     */
-    public function getListDatabasesSQL()
-    {
-        throw DBALException::notSupported(__METHOD__);
-    }
-
-    /**
-     * {@inheritDoc}
-     */
-    public function getListSequencesSQL($database)
-    {
-        throw DBALException::notSupported(__METHOD__);
-    }
-
-    /**
-     * {@inheritDoc}
-     */
-    public function getListTableConstraintsSQL($table)
-    {
-        throw DBALException::notSupported(__METHOD__);
-    }
-
     /**
      * This code fragment is originally from the Zend_Db_Adapter_Db2 class.
      *
@@ -297,14 +273,6 @@ class DB2Platform extends AbstractPlatform
         return "SELECT NAME FROM SYSIBM.SYSTABLES WHERE TYPE = 'T'";
     }
 
-    /**
-     * {@inheritDoc}
-     */
-    public function getListUsersSQL()
-    {
-        throw DBALException::notSupported(__METHOD__);
-    }
-
     /**
      * {@inheritDoc}
      */
@@ -383,22 +351,6 @@ class DB2Platform extends AbstractPlatform
         return "DROP VIEW ".$name;
     }
 
-    /**
-     * {@inheritDoc}
-     */
-    public function getDropSequenceSQL($sequence)
-    {
-        throw DBALException::notSupported(__METHOD__);
-    }
-
-    /**
-     * {@inheritDoc}
-     */
-    public function getSequenceNextValSQL($sequenceName)
-    {
-        throw DBALException::notSupported(__METHOD__);
-    }
-
     /**
      * {@inheritDoc}
      */