Hello, I tried to generate torch model and use it in C++ code.

Since I want to set dtype of all variables in model to double, I use `torch.set_default_dtype(torch.float64)`

in my python code for generating torchscript file.

And I create C++ variable with dtype double:

```
torch::Tensor i_tensor = torch::zeros({3,10}, torch::dtype(torch::kFloat64));
auto i_tensor_a = i_tensor.accessor<double,2>();
```

But I face the error like below:

```
terminate called after throwing an instance of 'std::runtime_error'
what(): The following operation failed in the TorchScript interpreter.
Traceback of TorchScript (most recent call last):
RuntimeError: The following operation failed in the TorchScript interpreter.
Traceback of TorchScript (most recent call last):
File "<string>", line 3, in <foward op>
def addmm(self: Tensor, mat1: Tensor, mat2: Tensor, beta: number = 1.0, alpha: number = 1.0):
return self + mat1.mm(mat2)
~~~~~~~ <--- HERE
def batch_norm(input : Tensor, running_mean : Optional[Tensor], running_var : Optional[Tensor], training : bool, momentum : float, eps : float) -> Tensor:
RuntimeError: Expected object of scalar type Float but got scalar type Double for argument #3 'mat2' in call to _th_addmm_out
```

How can I fix it?

Note: It works well when I change double to float in C++ code and remove the line contains `set_default_dtype`