chore: IArchTaskBarReeiver subclasses should return nullptr for empty icon not NULL

src/cmd/deskflowc/OSXClientTaskBarReceiver.cpp

@@ -52,7 +52,7 @@ void OSXClientTaskBarReceiver::primaryAction()
 
 IArchTaskBarReceiver::Icon OSXClientTaskBarReceiver::getIcon() const
 {
-  return NULL;
+  return nullptr;
 }
 
 IArchTaskBarReceiver *createTaskBarReceiver(const BufferedLogOutputter *logBuffer, IEventQueue *events)

src/cmd/deskflowc/XWindowsClientTaskBarReceiver.cpp

@@ -52,7 +52,7 @@ void CXWindowsClientTaskBarReceiver::primaryAction()
 
 IArchTaskBarReceiver::Icon CXWindowsClientTaskBarReceiver::getIcon() const
 {
-  return NULL;
+  return nullptr;
 }
 
 IArchTaskBarReceiver *createTaskBarReceiver(const BufferedLogOutputter *logBuffer, IEventQueue *events)

src/cmd/deskflows/OSXServerTaskBarReceiver.cpp

@@ -52,7 +52,7 @@ void OSXServerTaskBarReceiver::primaryAction()
 
 IArchTaskBarReceiver::Icon OSXServerTaskBarReceiver::getIcon() const
 {
-  return NULL;
+  return nullptr;
 }
 
 IArchTaskBarReceiver *createTaskBarReceiver(const BufferedLogOutputter *logBuffer, IEventQueue *events)

src/cmd/deskflows/XWindowsServerTaskBarReceiver.cpp

@@ -52,7 +52,7 @@ void CXWindowsServerTaskBarReceiver::primaryAction()
 
 IArchTaskBarReceiver::Icon CXWindowsServerTaskBarReceiver::getIcon() const
 {
-  return NULL;
+  return nullptr;
 }
 
 IArchTaskBarReceiver *createTaskBarReceiver(const BufferedLogOutputter *logBuffer, IEventQueue *events)