Add getter for QSizePolicy to SpacerItem

Change allows to change width and height with
changeSize() method without changing size policy.

Task-number: QTBUG-38518
Change-Id: I3eabb5fbfd9792c57c0a533ce14ec99b64603631
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>
Reviewed-by: Jan Arve Sæther <jan-arve.saether@theqtcompany.com>

src/widgets/kernel/qlayoutitem.cpp

@@ -340,6 +340,14 @@ QSpacerItem * QSpacerItem::spacerItem()
     return this;
 }
 
+/*!
+    Returns the size policy of this item.
+*/
+QSizePolicy QSpacerItem::sizePolicy() const
+{
+    return sizeP;
+}
+
 /*!
     If this item is a QWidget, it is returned as a QWidget; otherwise
     0 is returned. This function provides type-safe casting.

src/widgets/kernel/qlayoutitem.h

@@ -102,6 +102,7 @@ public:
     void setGeometry(const QRect&);
     QRect geometry() const;
     QSpacerItem *spacerItem();
+    QSizePolicy sizePolicy() const;
 
 private:
     int width;