COMPAT: Cast to string before raise in read_stata
In `pandas.io.stata::StataReader::_read_old_header` we
try to raise a ValueError.

I'm working on making a test, but this is buried pretty deep.
For now, `typlist` has type `List[int]`. We call

```python
','.join(typlist)
```

which errors on py3 (and python 2 I guess?). This came up in #13856, see https://travis-ci.org/pandas-dev/pandas/jobs/175705122#L1284 for the failure.

@kshedden any memory of writing this code? This is a bare `except` but it looks like the only exception that would trigger this is an `IndexError` when something in `typlist` is out of bounds on `self.TYPE_MAP`. Any hints on writing a test to exercise this code? If not I'll dig in more tonight.