Fix warn conversion from 'size_t' to 'int'. add comment for doxygen

modules/flann/include/opencv2/flann/lsh_index.h

@@ -106,6 +106,8 @@ public:
 
     /**
     * Implementation for the LSH addable indexes after that.
+    * @param wholeData whole dataset with the input features
+    * @param additionalData additional dataset with the input features
     */
     void addIndex(const Matrix<ElementType>& wholeData, const Matrix<ElementType>& additionalData)
     {
@@ -113,7 +115,7 @@ public:
         for (unsigned int i = 0; i < table_number_; ++i) {
             lsh::LshTable<ElementType>& table = tables_[i];
             // Add the features to the table with indexed offset
-            table.add(wholeData.rows - additionalData.rows, additionalData);
+            table.add((int)(wholeData.rows - additionalData.rows), additionalData);
         }
         dataset_ = wholeData;
     }

modules/flann/include/opencv2/flann/lsh_table.h

@@ -192,6 +192,7 @@ public:
     }
 
     /** Add a set of features to the table
+     * @param indexed_ofst previous indexed offset
      * @param dataset the values to store
      */
     void add(int indexed_ofst, Matrix<ElementType> dataset)