Suppress "statement is unreachable" warning (#49495)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/49495
Compiling PyTorch currently generates a large number of warnings like this:
```
caffe2/aten/src/ATen/core/builtin_function.h(105): warning: statement is unreachable
```
The offending code
```
std::string pretty_print_schema() const override {
TORCH_INTERNAL_ASSERT(false);
return "";
}
```
has an unreachable return which prevents a "no return" warning.
We resolve the situation by using NVCC's pragma system to suppress this warning within this function.
Test Plan:
The warning appears when running:
```
buck build mode/dev-nosan //caffe2/torch/fb/sparsenn:test
```
As well as a number of other build commands.
Reviewed By: ngimel
Differential Revision: D25546542
fbshipit-source-id: 71cddd4fdb5fd16022a6d7b2daf0e6d55e6e90e2
