Fix linux warns & more cosmetics.

modules/xfeatures2d/src/daisy.cpp

@@ -859,11 +859,11 @@ private:
       CV_Assert(layers!=NULL);
       memset(layers,0,sizeof(T)*data_size*layer_no);
 
-      bool empty=false;
+      bool was_empty = false;
       T* work=NULL;
       if( lwork < 3*data_size ) {
          work = new T[3*data_size];
-         empty=true;
+         was_empty = true;
       }
 
       // // smooth the data matrix
@@ -894,7 +894,7 @@ private:
             else            layer_l[index] = 0;
          }
       }
-      if( empty ) delete []work;
+      if( was_empty ) delete []work;
     }
 
     // casts a type T2 array into a type T1 array.