Use simpler Plugin::initialize() when feasible

Change-Id: I567965d266f20526bda9f823e31a04b354d53fb1
Reviewed-by: Eike Ziller <eike.ziller@qt.io>

src/plugins/cvs/cvsplugin.cpp

@@ -480,12 +480,9 @@ CvsPlugin::~CvsPlugin()
     dd = nullptr;
 }
 
-bool CvsPlugin::initialize(const QStringList &arguments, QString *errorMessage)
+void CvsPlugin::initialize()
 {
-    Q_UNUSED(arguments)
-    Q_UNUSED(errorMessage)
     dd = new CvsPluginPrivate;
-    return true;
 }
 
 void CvsPlugin::extensionsInitialized()