added BruteForceMatcher_GPU (for legacy)

modules/gpu/include/opencv2/gpu/gpu.hpp

@@ -1371,6 +1371,30 @@ private:
     std::vector<GpuMat> trainDescCollection;
 };
 
+template <class Distance> 
+class CV_EXPORTS BruteForceMatcher_GPU;
+
+template <typename T>
+class CV_EXPORTS BruteForceMatcher_GPU< L1<T> > : public BFMatcher_GPU
+{
+public:
+    explicit BruteForceMatcher_GPU() : BFMatcher_GPU(NORM_L1) {}
+    explicit BruteForceMatcher_GPU(L1<T> /*d*/) : BFMatcher_GPU(NORM_L1) {}
+};
+template <typename T>
+class CV_EXPORTS BruteForceMatcher_GPU< L2<T> > : public BFMatcher_GPU
+{
+public:
+    explicit BruteForceMatcher_GPU() : BFMatcher_GPU(NORM_L2) {}
+    explicit BruteForceMatcher_GPU(L2<T> /*d*/) : BFMatcher_GPU(NORM_L2) {}
+};
+template <> class CV_EXPORTS BruteForceMatcher_GPU< Hamming > : public BFMatcher_GPU
+{
+public:
+    explicit BruteForceMatcher_GPU() : BFMatcher_GPU(NORM_HAMMING) {}
+    explicit BruteForceMatcher_GPU(Hamming /*d*/) : BFMatcher_GPU(NORM_HAMMING) {}
+};
+
 ////////////////////////////////// CascadeClassifier_GPU //////////////////////////////////////////
 // The cascade classifier class for object detection.
 class CV_EXPORTS CascadeClassifier_GPU