tools: use python on path

Use the canonical syntax to specify the python executable to use.

Avoids a fatal error if /usr/bin/python is a too old version (< 2.7).

Change-Id: I3e8affb52be993d35c0dcf90774d962a59ef5635

tools/util_test.py

diff --git a/tools/util_test.py b/tools/util_test.py
index f116171..30647ba 100644
--- a/tools/util_test.py
+++ b/tools/util_test.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 # Copyright (C) 2013 The Android Open Source Project
 #
 # Licensed under the Apache License, Version 2.0 (the "License");