Add overrides and switch to nullptr keyword for all files

Adds remaining missing overrides and nullptr usages, missed due to
an extreme failure in tool usage.

Change-Id: I56abd72975a3999ad13330003c348db40f59aebf
diff --git a/libs/hwui/Animator.h b/libs/hwui/Animator.h
index aa3d301..1b3d8e7 100644
--- a/libs/hwui/Animator.h
+++ b/libs/hwui/Animator.h
@@ -64,7 +64,7 @@
 
     void attach(RenderNode* target);
     virtual void onAttached() {}
-    void detach() { mTarget = 0; }
+    void detach() { mTarget = nullptr; }
     void pushStaging(AnimationContext& context);
     bool animate(AnimationContext& context);
 
@@ -139,10 +139,10 @@
     ANDROID_API virtual uint32_t dirtyMask();
 
 protected:
-    virtual float getValue(RenderNode* target) const;
-    virtual void setValue(RenderNode* target, float value);
-    virtual void onAttached();
-    virtual void onStagingPlayStateChanged();
+    virtual float getValue(RenderNode* target) const override;
+    virtual void setValue(RenderNode* target, float value) override;
+    virtual void onAttached() override;
+    virtual void onStagingPlayStateChanged() override;
 
 private:
     typedef bool (RenderProperties::*SetFloatProperty)(float value);
@@ -162,8 +162,8 @@
     ANDROID_API virtual uint32_t dirtyMask();
 
 protected:
-    virtual float getValue(RenderNode* target) const;
-    virtual void setValue(RenderNode* target, float value);
+    virtual float getValue(RenderNode* target) const override;
+    virtual void setValue(RenderNode* target, float value) override;
 private:
     sp<CanvasPropertyPrimitive> mProperty;
 };
@@ -181,8 +181,8 @@
     ANDROID_API virtual uint32_t dirtyMask();
 
 protected:
-    virtual float getValue(RenderNode* target) const;
-    virtual void setValue(RenderNode* target, float value);
+    virtual float getValue(RenderNode* target) const override;
+    virtual void setValue(RenderNode* target, float value) override;
 private:
     sp<CanvasPropertyPaint> mProperty;
     PaintField mField;
@@ -196,8 +196,8 @@
     ANDROID_API virtual uint32_t dirtyMask();
 
 protected:
-    virtual float getValue(RenderNode* target) const;
-    virtual void setValue(RenderNode* target, float value);
+    virtual float getValue(RenderNode* target) const override;
+    virtual void setValue(RenderNode* target, float value) override;
 
 private:
     int mCenterX, mCenterY;