Here are three patches for errors I found by running random tests on windows:

1 - bltin.diff: MSVC compiler does not accept #ifdef inside macro parameters (http://support.microsoft.com/kb/38291). 
Seems ugly, but I think I respected the spirit of the PyDoc_ macros.

2 - unicode.diff: a 'off-by-one' pointer error in PyUnicode_FromFormat that crashes the interpreter when an item cannot be converted by %U:
print(OSError(1, str8(b'\xe9')))

3 - windowserror.diff: UnicodeDecodeError is raised when the error message returned by the w32 function FormatMessage() contains French accented characters.
(it crashed the interpreted before patch#2...)