Fix deletion in kmeans_index.h

Author: tkoeppe

src/cpp/flann/algorithms/kmeans_index.h

@@ -525,7 +525,7 @@ class KMeansIndex : public NNIndex<Distance>
 
         node->variance = variance;
         node->radius = radius;
-        delete node->pivot;
+        delete[] node->pivot;
         node->pivot = mean;
     }