message: Fix MeanStddevNormalization local reductions.
  mem_fence is only ordering memory within a work*item*, not a workgroup.
diff: @@ -50,13 +50,13 @@ std::string GetReduceCode() {
  static inline float local_reduce(float input, __local float* tmp) {
  const int local_id = get_local_id(0);
  tmp[local_id] = input;
  - mem_fence(CLK_LOCAL_MEM_FENCE);
  + barrier(CLK_LOCAL_MEM_FENCE);
  int reduction_size = get_local_size(0) / 2;
  while (reduction_size > 0) {
  if (local_id < reduction_size) {
  tmp[local_id] += tmp[local_id + reduction_size];
  }
  - mem_fence(CLK_LOCAL_MEM_FENCE);
  + barrier(CLK_LOCAL_MEM_FENCE);
  reduction_size /= 2;
  }
  return tmp[0];
  