修复bug：当包含外键的一个配置先无效再有效时，即配置ID重用，外键生成的本地文件会被错误的删除。

test/perf_test_maatframe.cpp

@@ -84,9 +84,7 @@ protected:
 		
 		const char* foregin_dir="./foreign_files/";	
 		Maat_set_feather_opt(_shared_feather, MAAT_OPT_FOREIGN_CONT_DIR, foregin_dir, strlen(foregin_dir)+1);
-		int linger_timeout=2;
-		Maat_set_feather_opt(_shared_feather, MAAT_OPT_FOREIGN_CONT_LINGER, &linger_timeout, sizeof(linger_timeout));
-
+	
 		Maat_cmd_flushDB(_shared_feather);
 		Maat_initiate_feather(_shared_feather);
 	}