message: Exclude graph construction time from all nn_ops benchmarks.
  This matches the other benchmarks in nn_ops_test.cc, and should reduce noise in the regression tests.
diff: @@ -108,6 +108,7 @@ static void BM_ConvFloat(int iters, int batch, int rows, int cols, int in_depth,
  CONV_OP op, int num_threads, int stride,
  Padding padding, bool use_gpu, DataType data_type,
  const string& label) {
  + testing::StopTiming();
  if (!IsGoogleCudaEnabled() && use_gpu) {
  testing::SetLabel(
  strings::StrCat("Skipping GPU test (no --config=cuda): ", label));
  @@ -221,6 +222,7 @@ static void BM_ConvFloat(int iters, int batch, int rows, int cols, int in_depth,
  string device = use_gpu ? "gpu" : "cpu";
  testing::UseRealTime();
  + testing::StartTiming();
  test::Benchmark(device, g, &options).Run(iters);
  testing::ItemsProcessed(num_ops * iters);
  }
  @@ -502,6 +504,7 @@ static void BM_ConvFloatDepthwise(int iters, int batch, int rows, int cols,
  int filter_cols, DEPTHWISE_CONV_OP op,
  int num_threads, int stride, Padding padding,
  bool use_gpu, const string& label) {
  + testing::StopTiming();
  if (!IsGoogleCudaEnabled() && use_gpu) {
  testing::SetLabel(
  strings::StrCat("Skipping GPU test (no --config=cuda): ", label));
  @@ -601,6 +604,7 @@ static void BM_ConvFloatDepthwise(int iters, int batch, int rows, int cols,
  string device = use_gpu ? "gpu" : "cpu";
  testing::UseRealTime();
  + testing::StartTiming();
  test::Benchmark(device, g, &options).Run(iters);
  testing::ItemsProcessed(num_ops * iters);
  }
  