python3: add raw prefix in cases harder to analyze at the token level The `byteify-strings.py` script would be a lot more complicated if it had to do backtracking and other more advanced static analysis to figure our those cases, so we have to add the raw prefix to those cases manually.

# name space package to host third party extensions
from __future__ import absolute_import
import pkgutil
__path__ = pkgutil.extend_path(__path__, __name__)