[Python-3000] Py3k_struni additional test failures under cygwin

["Martin v. Löwis"]

>> If I patch io.py to default to "utf-8" rather than using the filesystem
>> encoding (ascii), that fixes a few more things. (test_coding.py and
>> test_minidom.py)
> 
> How come the filesystem decoding is set to ASCII?

I guess there are two problems: a) MS_WINDOWS isn't defined, and the
relevant code in bltinmodule.c doesn't special-case cygwin, and b)
setlocale is defined on Cygwin, but doesn't work.

>> (For whats its worth, Cygwin's python 2.5 (as installed on my system) fails
>> 2 of the tests in it's version of test_mailbox.py, both with "IOError:
>> [Errno 13] Permission denied").

I found that in many cases, this is a virus scanner or the indexing
service interfering. They open the file, and then the test suite cannot
delete it.

Regards,
Martin