Move X11Client::wantsShadowToBeRendered to AbstractClient

Otherwise only X11 windows will lose server-side drop-shadows when the
maximized mode changes.

BUG: 434213

src/abstract_client.cpp

@@ -3770,4 +3770,9 @@ void AbstractClient::cleanTabBox()
 #endif
 }
 
+bool AbstractClient::wantsShadowToBeRendered() const
+{
+    return !isFullScreen() && maximizeMode() != MaximizeFull;
+}
+
 }

src/abstract_client.h

@@ -747,6 +747,7 @@ public:
     void processDecorationMove(const QPoint &localPos, const QPoint &globalPos);
     bool processDecorationButtonPress(QMouseEvent *event, bool ignoreMenu = false);
     void processDecorationButtonRelease(QMouseEvent *event);
+    bool wantsShadowToBeRendered() const override;
 
     /**
      * TODO: fix boolean traps

src/x11client.cpp

@@ -1349,11 +1349,6 @@ void X11Client::checkNoBorder()
     setNoBorder(app_noborder);
 }
 
-bool X11Client::wantsShadowToBeRendered() const
-{
-    return !isFullScreen() && maximizeMode() != MaximizeFull;
-}
-
 void X11Client::updateShape()
 {
     if (shape()) {

src/x11client.h

@@ -259,7 +259,6 @@ public:
     QRect transparentRect() const override;
 
     bool isClientSideDecorated() const;
-    bool wantsShadowToBeRendered() const override;
 
     void layoutDecorationRects(QRect &left, QRect &top, QRect &right, QRect &bottom) const override;