Fix Windows DLL build

In Windows DLL builds we inject operator new/delete definitions into
classes with a leak detector. This requires that all inheritance from
such classes must be public, and classes inheriting from multiple such
classes must disambiguate between the base's operators.

modules/juce_audio_processors/processors/juce_AudioProcessorGraph.cpp

@@ -1405,7 +1405,7 @@ bool AudioProcessorGraph::Connection::operator< (const Connection& other) const
 }
 
 //==============================================================================
-class AudioProcessorGraph::Pimpl : private AsyncUpdater
+class AudioProcessorGraph::Pimpl : public AsyncUpdater
 {
 public:
     explicit Pimpl (AudioProcessorGraph& o) : owner (&o) {}

modules/juce_audio_processors/processors/juce_GenericAudioProcessorEditor.cpp

@@ -102,6 +102,8 @@ class ParameterComponent : public Component,
 {
 public:
     using ParameterListener::ParameterListener;
+
+    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (ParameterComponent)
 };
 
 //==============================================================================

modules/juce_core/threads/juce_HighResolutionTimer.cpp

@@ -23,7 +23,7 @@
 namespace juce
 {
 
-class HighResolutionTimer::Pimpl : private Thread
+class HighResolutionTimer::Pimpl : public Thread
 {
     using steady_clock = std::chrono::steady_clock;
     using milliseconds = std::chrono::milliseconds;