Remove the remnant code (test=develop)

Author: yihuaxu

paddle/fluid/operators/stack_op.h

@@ -72,25 +72,6 @@ class StackOpMaker : public framework::OpProtoAndCheckerMaker {
   }
 };
 
-template <typename VecXType, typename T>
-struct StackFunctor {
-  HOSTDEVICE StackFunctor(const VecXType &x, T *y, int n, int post)
-      : x_(x), y_(y), n_(n), post_(post) {}
-
-  HOSTDEVICE void operator()(int idx) {
-    int i = idx / (n_ * post_);
-    int which_x = idx / post_ - i * n_;
-    int x_index = i * post_ + idx % post_;
-    y_[idx] = x_[which_x][x_index];
-  }
-
- private:
-  VecXType x_;
-  T *y_;
-  int n_;
-  int post_;
-};
-
 template <typename VecDxType, typename T>
 struct StackGradFunctor {
   HOSTDEVICE StackGradFunctor(const VecDxType &dx, const T *dy, int n, int post)
@@ -110,14 +91,6 @@ struct StackGradFunctor {
   int post_;
 };
 
-template <typename DeviceContext, typename VecXType, typename T>
-static inline void StackFunctorForRange(const DeviceContext &ctx,
-                                        const VecXType &x, T *y, int total_num,
-                                        int n, int post) {
-  platform::ForRange<DeviceContext> for_range(ctx, total_num);
-  for_range(StackFunctor<VecXType, T>(x, y, n, post));
-}
-
 template <typename DeviceContext, typename VecDxType, typename T>
 static inline void StackGradFunctorForRange(const DeviceContext &ctx,
                                             const VecDxType &dx, const T *dy,