WSAPoll: disabled on all windows builds

Due to WSAPoll bugs, libcurl does not work as intended. When the cURL
library is used to setup a connection to an incorrect port, normally the
result is CURLE_COULDNT_CONNECT, /* 7 */, but due to the bug in WSAPoll,
the result now is CURLE_OPERATION_TIMEDOUT, /* 28 - the timeout time was
reached */.

On August 1, Jan Koen Annot opened a case for this to Microsoft Premier
Online (https://premier.microsoft.com/).  The support engineer handling
the case wrote that the case description is quite clear.  He will try to
reproduce the issue and then proceed with troubleshooting it.

Reported by: Jan Koen Annot
Bug: http://curl.haxx.se/mail/lib-2012-07/0310.html