Import pywintypes first.

Mark Hammond's checkin comment for Zope 2.7's WinSignalHandler.py,
rev 1.1.2.2:

"""
As at pywin32-204, we must ensure pywintypes is the first win32 module
imported in our process, otherwise we can end up with 2 pywintypesxx.dll
instances in our process resulting in:
TypeError: The object is not a PySECURITY_ATTRIBUTES object
"""

Mysterious error popup boxes have also been seen, on boxes with a
pre-pywin32-204 installation leaving pywin32 DLLs in the system32
directory.