Fixed a few singletons which had forgotten to call clearSingletonInstance() in their destructors

modules/juce_events/native/juce_android_Messaging.cpp

@@ -58,9 +58,10 @@ namespace Android
 
     struct Handler
     {
-        JUCE_DECLARE_SINGLETON (Handler, false)
-
         Handler() : nativeHandler (getEnv()->NewObject (JNIHandler, JNIHandler.constructor)) {}
+        ~Handler() { clearSingletonInstance(); }
+
+        JUCE_DECLARE_SINGLETON (Handler, false)
 
         bool post (jobject runnable)
         {
@@ -86,6 +87,7 @@ struct AndroidMessageQueue     : private Android::Runnable
     ~AndroidMessageQueue()
     {
         jassert (MessageManager::getInstance()->isThisTheMessageThread());
+        clearSingletonInstance();
     }
 
     bool post (MessageManager::MessageBase::Ptr&& message)

modules/juce_events/native/juce_win32_WinRTWrapper.h

@@ -60,6 +60,8 @@ public:
     {
         if (winRTHandle != nullptr)
             ::FreeLibrary (winRTHandle);
+
+        clearSingletonInstance();
     }
 
     String hStringToString (HSTRING hstr)

modules/juce_gui_basics/misc/juce_JUCESplashScreen.cpp

@@ -73,6 +73,9 @@ struct ReportingThread;
 struct ReportingThreadContainer  : public ChangeListener,
                                    public DeletedAtShutdown
 {
+    ReportingThreadContainer() {}
+    ~ReportingThreadContainer() { clearSingletonInstance(); }
+
     void sendReport (String, String&, StringPairArray&);
     void changeListenerCallback (ChangeBroadcaster*) override;
 

modules/juce_gui_basics/native/juce_win32_Windowing.cpp

@@ -763,6 +763,11 @@ private:
         tipInvocation.CoCreateInstance (ITipInvocation::getCLSID(), CLSCTX_INPROC_HANDLER | CLSCTX_LOCAL_SERVER);
     }
 
+    ~OnScreenKeyboard()
+    {
+        clearSingletonInstance();
+    }
+
     void timerCallback() override
     {
         stopTimer();