Portable Python script across Python version

StringIO is obsoleted in Python3, replaced by io.BytesIO or io.StringIO depending on the use.

Differential Revision: https://reviews.llvm.org/D55196

git-svn-id: svn://svn.chromium.org/llvm-project/cfe/trunk/tools/clang-format@350318 0b72dbe1-c17f-4bc7-b9db-2b4152be0356
1 file changed