Fixed crash in BruteForceMatcher::clone

modules/features2d/include/opencv2/features2d/features2d.hpp

@@ -2367,6 +2367,7 @@ Ptr<DescriptorMatcher> BruteForceMatcher<Distance>::clone( bool emptyTrainData )
     BruteForceMatcher* matcher = new BruteForceMatcher(distance);
     if( !emptyTrainData )
     {
+        matcher->trainDescCollection.resize(trainDescCollection.size());
         std::transform( trainDescCollection.begin(), trainDescCollection.end(),
                         matcher->trainDescCollection.begin(), clone_op );
     }