Add clarifying note to test_print_statement.

tools/lint/tests/test_file_lints.py

@@ -633,6 +633,8 @@ def test_late_timeout():
             ]
 
 
+# Note: This test checks the print *statement* (which doesn't exist in python 3).
+#       The print *function* is checked in test_print_function below.
 @pytest.mark.skipif(six.PY3, reason="Cannot parse print statements from python 3")
 def test_print_statement():
     error_map = check_with_files(b"def foo():\n  print 'statement'\n  print\n")