non-ascii characters in win32 installation path prevents PySide import

If you install PySide to a non-standard location with non-ascii characters in the path, the PySide import fails. An example of this is a frozen python application installed in such a path.

On Windows, PySide._util has code to get the correct-cased filename. This calls unicode functions but assumes the original __file__ is all ascii. This may not be the case.

This presumably is only a bug for Python 2.