feature2d: do not compute keypoints orientation twice

* always compute keypoints orientation, when computing keypoints
* do not recompute keypoint orientation when computing descriptors

this allows to test detection and extraction separately

modules/features2d/src/akaze.cpp

@@ -200,8 +200,7 @@ namespace cv
             if (!useProvidedKeypoints)
             {
                 impl.Feature_Detection(keypoints);
-                if( !descriptors.needed() )
-                    impl.Compute_Keypoints_Orientation(keypoints);
+                impl.Compute_Keypoints_Orientation(keypoints);
             }
 
             if (!mask.empty())

modules/features2d/src/kaze/AKAZEFeatures.cpp

@@ -549,7 +549,6 @@ public:
   {
     for (int i = range.start; i < range.end; i++)
     {
-      AKAZEFeatures::Compute_Main_Orientation((*keypoints_)[i], *evolution_);
       Get_MSURF_Descriptor_64((*keypoints_)[i], descriptors_->ptr<float>(i));
     }
   }
@@ -643,7 +642,6 @@ public:
   {
     for (int i = range.start; i < range.end; i++)
     {
-      AKAZEFeatures::Compute_Main_Orientation((*keypoints_)[i], *evolution_);
       Get_MLDB_Full_Descriptor((*keypoints_)[i], descriptors_->ptr<unsigned char>(i));
     }
   }