Change WId to be a quintptr.

Fix compilation with MinGW-w64: Use quintptr instead of
unsigned long as WId needs to be able to cast to
HWND which is a 64-bit pointer on Windows 64-bit.

Acked-by: Samuel Rødal <samuel.rodal@nokia.com>

Change-Id: I7bbe83ce02b739eb04218ca4b6b478509347d515
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@nokia.com>

src/gui/kernel/qwindowdefs.h

@@ -42,6 +42,7 @@
 #ifndef QWINDOWDEFS_H
 #define QWINDOWDEFS_H
 
+#include <QtCore/qglobal.h>
 #include <QtCore/qobjectdefs.h>
 #include <QtCore/qnamespace.h>
 
@@ -99,7 +100,7 @@ QT_END_HEADER
 
 
 
-typedef unsigned long  WId;
+typedef QT_PREPEND_NAMESPACE(quintptr) WId;