c10::nullopt -> std::nullopt (#1032)

Summary:
X-link: pytorch/torchrec#2515

X-link: pytorch/executorch#6461

X-link: pytorch/audio#3848

X-link: pytorch/ao#1151

Pull Request resolved: #1032

Reviewed By: houseroad

Differential Revision: D64835967

fbshipit-source-id: 9f9f65335aaf5497680561027ef9314e4b36f8d9

fx2ait/fx2ait/csrc/AITModelImpl.cpp

@@ -366,7 +366,7 @@ std::vector<torch::Tensor> AITModelImpl::processOutputs(
       output.unsafeGetTensorImpl()->set_sizes_contiguous(size);
     }
 
-    if (floating_point_output_dtype_ != c10::nullopt &&
+    if (floating_point_output_dtype_ != std::nullopt &&
         output.is_floating_point()) {
       outputs.emplace_back(output.to(*floating_point_output_dtype_));
     } else {
@@ -394,7 +394,7 @@ std::vector<AITData> AITModelImpl::processInputs(
     auto input_name = input_names_[python_input_idx];
     const auto ait_input_idx = input_name_to_index_.at(input_name);
     auto& input = inputs[python_input_idx];
-    if (floating_point_input_dtype_ != c10::nullopt &&
+    if (floating_point_input_dtype_ != std::nullopt &&
         input.is_floating_point()) {
       // Need to keep input alive; cannot just stash result of to()
       // call in a local!