HostOsInfo: compile, #define _WIN32_WINNT for GetNativeSystemInfo

Change-Id: I012afcdb53b6a081eabfb0843236a25dd27d6ddb
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@digia.com>
Reviewed-by: Daniel Teske <daniel.teske@digia.com>

src/libs/utils/hostosinfo.cpp

@@ -30,7 +30,9 @@
 #include "hostosinfo.h"
 
 #ifdef Q_OS_WIN
-#include <windows.h>
+#undef _WIN32_WINNT
+#define _WIN32_WINNT 0x0501 /* WinXP, needed for GetNativeSystemInfo() */
+#include <qt_windows.h>
 #endif
 
 using namespace Utils;