COMP: implement pure virtual method GetVotes when using OpenCV 4

Modules/Learning/Supervised/include/otbCvRTreesWrapper.h

@@ -104,6 +104,10 @@ public:
   OTB_CV_WRAP_CSTREF_GET(std::vector<cv::ml::DTrees::Split>, Splits)
   OTB_CV_WRAP_CSTREF_GET(std::vector<int>, Subsets)
 
+#ifdef OTB_OPENCV_4
+  virtual void getVotes(cv::InputArray samples, cv::OutputArray results, int flags) const override;
+#endif
+
   virtual cv::Mat getVarImportance() const override;
 
   virtual cv::String 	getDefaultName () const override;

Modules/Learning/Supervised/src/otbCvRTreesWrapper.cxx

@@ -197,6 +197,13 @@ cv::Mat CvRTreesWrapper::getVarImportance() const
   return m_Impl->getVarImportance();
 }
 
+#ifdef OTB_OPENCV_4
+void CvRTreesWrapper::getVotes(cv::InputArray samples, cv::OutputArray results, int flags) const
+{
+  m_Impl->getVotes(samples, results, flags);
+}
+#endif
+
 cv::String CvRTreesWrapper::getDefaultName () const
 {
   return m_Impl->getDefaultName();