Description:
------------
The phpinfo() output on Windows 8.1 and Windows Server 2012 R2 reports the OS as Windows 8 and Windows Server 2012.

This is due to the deprecation of GetVersionEx (which we are using) on these platforms - http://msdn.microsoft.com/en-us/library/windows/desktop/dn302074%28v=vs.85%29.aspx

Once we compile the Windows builds with the Visual Studio 2013 compiler and the Windows 8.1 SDK, _NT_TARGET_VERSION=$(_NT_TARGET_VERSION_LATEST) seems to help. However until then we need a different approach. 

VerifyVersionInfo (http://msdn.microsoft.com/en-us/library/windows/desktop/ms725491%28v=vs.85%29.aspx) looks like the best solution to me. It is slower than GetVersionEx, so we should only run it if we detect Windows 8/Server 2012 and then need to decide whether it's 8.1/2012 R2 instead. The attached patch proposes an implementation. 



Test script:
---------------
<?php
  phpinfo(INFO_GENERAL);

Expected result:
----------------
Output contains "Windows 8.1" on a Windows 8.1 machine.
Output contains "Windows Server 2012 R2" on a Windows Server 2012 R2 machine.

Actual result:
--------------
Output contains "Windows 8" (and not 8.1) on a Windows 8.1 machine.
Output contains "Windows Server 2012" (and not R2) on a Windows Server 2012 R2 machine.