small fix to AudioPluginFormatManager

juce_amalgamated.cpp

@@ -26417,6 +26417,7 @@ AudioPluginFormatManager::AudioPluginFormatManager() throw()
 
 AudioPluginFormatManager::~AudioPluginFormatManager() throw()
 {
+    clearSingletonInstance();
 }
 
 juce_ImplementSingleton_SingleThreaded (AudioPluginFormatManager);

src/juce_appframework/audio/plugins/juce_AudioPluginFormatManager.cpp

@@ -50,6 +50,7 @@ AudioPluginFormatManager::AudioPluginFormatManager() throw()
 
 AudioPluginFormatManager::~AudioPluginFormatManager() throw()
 {
+    clearSingletonInstance();
 }
 
 juce_ImplementSingleton_SingleThreaded (AudioPluginFormatManager);