fix missing import

Summary: public
shamecube

Reviewed By: martinoluca

Differential Revision: D2642075

fb-gh-sync-id: 627fdcf

infer/lib/python/inferTraceBugs

@@ -13,6 +13,7 @@ from __future__ import print_function
 from __future__ import unicode_literals
 
 import argparse
+import codecs
 import json
 import os
 import re