Drop Compositor::restartKWin

No longer needed as we don't need to switch the graphics system any more.

composite.cpp

@@ -762,14 +762,6 @@ void Compositor::setOverlayWindowVisibility(bool visible)
     }
 }
 
-void Compositor::restartKWin(const QString &reason)
-{
-    kDebug(1212) << "restarting kwin for:" << reason;
-    char cmd[1024]; // copied from crashhandler - maybe not the best way to do?
-    sprintf(cmd, "%s --replace &", QFile::encodeName(QCoreApplication::applicationFilePath()).constData());
-    system(cmd);
-}
-
 bool Compositor::isCompositingPossible() const
 {
     return CompositingPrefs::compositingPossible();

composite.h

@@ -274,13 +274,6 @@ private:
     void setCompositeTimer();
     bool windowRepaintsPending() const;
 
-    /**
-     * Restarts the Window Manager in case that the Qt's GraphicsSystem need to be changed
-     * for the chosen Compositing backend.
-     * @param reason The reason why the Window Manager is being restarted, this is logged
-     **/
-    void restartKWin(const QString &reason);
-
     /**
      * Whether the Compositor is currently suspended, 8 bits encoding the reason
      **/