QmlDesigner: Always use old syntax for Qt4MCU

Qt4MCU does require the signature for new syntax.

The signature is not used on most cases and supporting the
signature is not worth the effort at the moment.
Therefore we fall back to the old syntax for Qt4MCU.

Task-number: QDS-14904
Change-Id: Id0c5962ac91849897229ab9e816879e8089893ee
Reviewed-by: Aleksei German <aleksei.german@qt.io>
Reviewed-by: Marco Bubke <marco.bubke@qt.io>
(cherry picked from commit d8d184fb4f)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

src/plugins/qmldesigner/libs/designercore/model/signalhandlerproperty.cpp

@@ -2,8 +2,9 @@
 // SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
 
 #include "signalhandlerproperty.h"
-#include "internalproperty.h"
+#include "externaldependenciesinterface.h"
 #include "internalnode_p.h"
+#include "internalproperty.h"
 #include "model.h"
 #include "model_p.h"
 
@@ -64,6 +65,12 @@ bool SignalHandlerProperty::useNewFunctionSyntax()
     if (name().contains('.'))
         return false;
 
+    if (!view())
+        return false;
+
+    if (view()->externalDependencies().isQtForMcusProject())
+        return false;
+
     return parentModelNode().metaInfo().isQtQmlConnections();
 }