format and clean unused import

Signed-off-by: joejiong <1004691415qq@gmail.com>

Author: Joejiong

test/lit.cfg.py

@@ -1,7 +1,12 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
 import os
 import platform
-import lit.formats
+
 import lit.util
+import lit.formats
+
 from lit.llvm import llvm_config
 from lit.llvm.subst import ToolSubst
 from lit.llvm.subst import FindTool