Update platform classes to use OVERRIDE / FINAL when needed

Source/platform/audio/EqualPowerPanner.h

Index: Source/platform/audio/EqualPowerPanner.h
diff --git a/Source/platform/audio/EqualPowerPanner.h b/Source/platform/audio/EqualPowerPanner.h
index 4085c19e841c73934f28750242b69b78eaaf1353..ad453611ad704bf2e33a7f28e2108a6b9936b6bb 100644
--- a/Source/platform/audio/EqualPowerPanner.h
+++ b/Source/platform/audio/EqualPowerPanner.h
@@ -35,9 +35,9 @@ class PLATFORM_EXPORT EqualPowerPanner : public Panner {
 public:
     EqualPowerPanner(float sampleRate);
 
-    virtual void pan(double azimuth, double elevation, const AudioBus* inputBus, AudioBus* outputBuf, size_t framesToProcess);
+    virtual void pan(double azimuth, double elevation, const AudioBus* inputBus, AudioBus* outputBuf, size_t framesToProcess) OVERRIDE;
 
-    virtual void reset() { m_isFirstRender = true; }
+    virtual void reset() OVERRIDE { m_isFirstRender = true; }
 
     virtual double tailTime() const OVERRIDE { return 0; }
     virtual double latencyTime() const OVERRIDE { return 0; }