Move some decoration related signals from Client to AbstractClient

abstract_client.h

@@ -573,6 +573,10 @@ Q_SIGNALS:
     void clientStartUserMovedResized(KWin::AbstractClient*);
     void clientStepUserMovedResized(KWin::AbstractClient *, const QRect&);
     void clientFinishUserMovedResized(KWin::AbstractClient*);
+    void closeableChanged(bool);
+    void minimizeableChanged(bool);
+    void shadeableChanged(bool);
+    void maximizeableChanged(bool);
 
 protected:
     AbstractClient();

client.h

@@ -459,11 +459,6 @@ Q_SIGNALS:
     void blockingCompositingChanged(KWin::Client *client);
     void clientSideDecoratedChanged();
 
-    void closeableChanged(bool);
-    void minimizeableChanged(bool);
-    void shadeableChanged(bool);
-    void maximizeableChanged(bool);
-
 private:
     void exportMappingState(int s);   // ICCCM 4.1.3.1, 4.1.4, NETWM 2.5.1
     bool isManaged() const; ///< Returns false if this client is not yet managed