use extras/labels.json and not ./labels.json in romstr.py

original-commit-id: 58c696cfd3a024751d133ed9a9b6809b3a0ff36c

romstr.py

@@ -49,6 +49,8 @@ class RomStr(str):
         """ Loads labels from labels.json, or parses the source code file and
             generates new labels.
         """
+        filename = os.path.dirname(__file__) + "/" + filename
+
         # blank out the hash
         self.labels = {}