Portable Python script across Python version

Get rid of Python version specific shebang.

Differential Revision: https://reviews.llvm.org/D55207

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@350319 91177308-0d34-0410-b5e6-96231b3b80d8

utils/check_cfc/check_cfc.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python2.7
+#!/usr/bin/env python
 
 """Check CFC - Check Compile Flow Consistency
 

utils/check_cfc/obj_diff.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python2.7
+#!/usr/bin/env python
 
 from __future__ import absolute_import, division, print_function
 

utils/check_cfc/test_check_cfc.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python2.7
+#!/usr/bin/env python
 
 """Test internal functions within check_cfc.py."""