Debugger: Fix QGraphicsPolygonItem dumper for Qt6 64 bits

And effectively disable the 32bit version, too much effort for the gain.

Change-Id: Ia11da05f3d57feba915d6b2d2d9c901e5aec3433
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

share/qtcreator/debugger/qttypes.py

@@ -1666,13 +1666,20 @@ def qdump__QPolygon(d, value):
 
 def qdump__QGraphicsPolygonItem(d, value):
     (vtbl, dptr) = value.split('pp')
-    # Assume sizeof(QGraphicsPolygonItemPrivate) == 400
-    if d.ptrSize() == 8:
-        offset = 384
-    elif d.isWindowsTarget():
-        offset = 328 if d.isMsvcTarget() else 320
+    if d.qtVersion() >= 0x060000:
+        if d.ptrSize() == 8:
+            offset = 424 # sizeof(QGraphicsPolygonItemPrivate), the base
+        else:
+            # Chicken out. Not worth maintaining.
+            d.putPlainChildren(value)
+            return
     else:
-        offset = 308
+        if d.ptrSize() == 8:
+            offset = 384
+        elif d.isWindowsTarget():
+            offset = 328 if d.isMsvcTarget() else 320
+        else:
+            offset = 308
     data, size = d.vectorData(dptr + offset)
     d.putItemCount(size)
     d.putPlotData(data, size, d.createType('@QPointF'))