[cocos2dx] Fixed missing virtual method in SkeletonAnimation.

spine-cocos2dx/src/spine/SkeletonAnimation.h

@@ -67,6 +67,7 @@ public:
 	}
 
 	virtual void update (float deltaTime) override;
+	virtual void draw (cocos2d::Renderer* renderer, const cocos2d::Mat4& transform, uint32_t transformFlags) override;
 
 	void setAnimationStateData (spAnimationStateData* stateData);
 	void setMix (const std::string& fromAnimation, const std::string& toAnimation, float duration);