Fix :func:`io.BufferedReader.tell`, :func:`io.BufferedReader.seek`, :func:`_pyio.BufferedReader.tell`, :func:`io.BufferedRandom.tell`, :func:`io.BufferedRandom.seek` and :func:`_pyio.BufferedRandom.tell` being able to return negative offsets.
Fix :func:`io.BufferedReader.tell`, :func:`io.BufferedReader.seek`, :func:`_pyio.BufferedReader.tell`, :func:`io.BufferedRandom.tell`, :func:`io.BufferedRandom.seek` and :func:`_pyio.BufferedRandom.tell` being able to return negative offsets.