Python compat - no explicit reference to Python version

Update documentation and shebang.

Differential Revision: https://reviews.llvm.org/D56252

llvm-svn: 350327
diff --git a/llvm/utils/update_analyze_test_checks.py b/llvm/utils/update_analyze_test_checks.py
index 0463bc0..64e64e0 100755
--- a/llvm/utils/update_analyze_test_checks.py
+++ b/llvm/utils/update_analyze_test_checks.py
@@ -1,4 +1,4 @@
-#!/usr/bin/env python2.7
+#!/usr/bin/env python
 
 """A script to generate FileCheck statements for 'opt' analysis tests.