Fix a memory leak in ALTER TABLE

Closes #965

Author: FaramosCZ

storage/innobase/btr/btr0bulk.cc

@@ -836,6 +836,7 @@ BtrBulk::insert(
 						level, m_flush_observer));
 		err = new_page_bulk->init();
 		if (err != DB_SUCCESS) {
+			UT_DELETE(new_page_bulk);
 			return(err);
 		}