fixed compile error and warning

modules/tracking/src/TrackingFunctionPF.hpp

@@ -9,6 +9,7 @@ namespace cv{
         public:
             TrackingFunctionPF(const Mat& chosenRect);
             void update(const Mat& image);
+            int getDims() const { return 4; }
             double calc(const double* x) const;
             void correctParams(double* pt)const;
         private:

modules/xphoto/src/gcgraph.hpp

@@ -254,7 +254,7 @@ TWeight GCGraph<TWeight>::maxFlow()
                 minWeight = MIN(minWeight, weight);
                 CV_Assert( minWeight > 0 );
             }
-            weight = abs( TWeight(v->weight) );
+            weight = std::abs( TWeight(v->weight) );
             minWeight = MIN(minWeight, weight);
             CV_Assert( minWeight > 0 );
         }