GetWindowsDirectory() needed
Imported from http://bugzilla.roxen.com/bugzilla/show_bug.cgi?id=793
Reported by Johan Schön js@roxen.com
Roxen needs a wrapper for the (pretty simple) win32 function GetWindowsDirectory():
http://msdn.microsoft.com/library/psdk/sysmgmt/sysinfo_4k55.htm