Fix cmake backslash syntax error on Windows. (#24420)
Summary:
```
[1/1424] Building NVCC (Device) object caffe2/CMakeFiles/torch.dir/operators/torch_generated_weighted_sample_op.cu.obj
CMake Warning (dev) at torch_generated_weighted_sample_op.cu.obj.Release.cmake:82 (set):
Syntax error in cmake code at
C:/Users/Ganzorig/pytorch/build/caffe2/CMakeFiles/torch.dir/operators/torch_generated_weighted_sample_op.cu.obj.Release.cmake:82
when parsing string
C:/Program Files/NVIDIA GPU Computing Toolkit/CUDA/v10.1/include;C:/Users/Ganzorig/pytorch/aten/src;C:/Users/Ganzorig/pytorch/build;C:/Users/Ganzorig/pytorch;C:/Users/Ganzorig/pytorch/cmake/../third_party/googletest/googlemock/include;C:/Users/Ganzorig/pytorch/cmake/../third_party/googletest/googletest/include;;C:/Users/Ganzorig/pytorch/third_party/protobuf/src;C:/Users/Ganzorig/pytorch/cmake/../third_party/benchmark/include;C:/Users/Ganzorig/pytorch/cmake/../third_party/eigen;C:/Users/Ganzorig/Anaconda3/envs/code/include;C:/Users/Ganzorig/Anaconda3/envs/code/lib/site-packages/numpy/core/include;C:/Users/Ganzorig/pytorch/cmake/../third_party/pybind11/include;C:/Users/Ganzorig/pytorch/cmake/../third_party/cub;C:/Users/Ganzorig/pytorch/build/caffe2/contrib/aten;C:/Users/Ganzorig/pytorch/third_party/onnx;C:/Users/Ganzorig/pytorch/build/third_party/onnx;C:/Users/Ganzorig/pytorch/third_party/foxi;C:/Users/Ganzorig/pytorch/build/third_party/foxi;C:/Program Files/NVIDIA GPU Computing Toolkit/CUDA/v10.1/include;C:/Users/Ganzorig/pytorch/caffe2/../torch/csrc/api;C:/Users/Ganzorig/pytorch/caffe2/../torch/csrc/api/include;C:/Program Files/NVIDIA Corporation/NvToolsExt/include;C:/Users/Ganzorig/pytorch/caffe2/aten/src/TH;C:/Users/Ganzorig/pytorch/build/caffe2/aten/src/TH;C:/Users/Ganzorig/pytorch/caffe2/../torch/../aten/src;C:/Users/Ganzorig/pytorch/build/caffe2/aten/src;C:/Users/Ganzorig/pytorch/build/aten/src;C:/Users/Ganzorig/pytorch/caffe2/../torch/../aten/src;C:/Users/Ganzorig/pytorch/build/caffe2/../aten/src;C:/Users/Ganzorig/pytorch/build/caffe2/../aten/src/ATen;C:/Users/Ganzorig/pytorch/build/aten/src;C:/Users/Ganzorig/pytorch/caffe2/../torch/csrc;C:/Users/Ganzorig/pytorch/caffe2/../torch/../third_party/miniz-2.0.8;C:/Users/Ganzorig/pytorch/caffe2/../torch/csrc/api;C:/Users/Ganzorig/pytorch/caffe2/../torch/csrc/api/include;C:/Users/Ganzorig/pytorch/build/caffe2/aten/src/TH;C:/Users/Ganzorig/pytorch/aten/src/TH;C:/Users/Ganzorig/pytorch/aten/src;C:/Users/Ganzorig/pytorch/build/caffe2/aten/src;C:/Users/Ganzorig/pytorch/build/aten/src;C:/Users/Ganzorig/pytorch/aten/src;C:/Users/Ganzorig/pytorch/aten/../third_party/catch/single_include;C:/Users/Ganzorig/pytorch/aten/src/ATen/..;C:/Users/Ganzorig/pytorch/build/caffe2/aten/src/ATen;C:/Users/Ganzorig/pytorch/third_party/miniz-2.0.8;C:/Users/Ganzorig/pytorch/caffe2/core/nomnigraph/include;C:/Users/Ganzorig/pytorch/caffe2/;C:/Program Files/NVIDIA GPU Computing Toolkit/CUDA/v10.1/include;C:/Users/Ganzorig/pytorch/build/caffe2/aten/src/TH;C:/Users/Ganzorig/pytorch/aten/src/TH;C:/Users/Ganzorig/pytorch/build/caffe2/aten/src/THC;C:/Users/Ganzorig/pytorch/aten/src/THC;C:/Users/Ganzorig/pytorch/aten/src/THCUNN;C:/Users/Ganzorig/pytorch/aten/src/ATen/cuda;C:/Users/Ganzorig/pytorch/build/caffe2/aten/src/TH;C:/Users/Ganzorig/pytorch/aten/src/TH;C:/Users/Ganzorig/pytorch/aten/src;C:/Users/Ganzorig/pytorch/build/caffe2/aten/src;C:/Users/Ganzorig/pytorch/build/aten/src;C:/Users/Ganzorig/pytorch/aten/src;C:/Users/Ganzorig/pytorch/aten/../third_party/catch/single_include;C:/Users/Ganzorig/pytorch/aten/src/ATen/..;C:/Users/Ganzorig/pytorch/build/caffe2/aten/src/ATen;C:/Users/Ganzorig/pytorch/third_party/protobuf/src;C:/Users/Ganzorig/pytorch/c10/../;C:/Users/Ganzorig/pytorch/build;C:/Users/Ganzorig/pytorch/third_party/cpuinfo/include;C:/Users/Ganzorig/pytorch/third_party/FP16/include;C:/Users/Ganzorig/pytorch/third_party/foxi;C:/Users/Ganzorig/pytorch/third_party/foxi;C:/Users/Ganzorig/pytorch/third_party/onnx;C:/Users/Ganzorig/pytorch/build/third_party/onnx;C:/Users/Ganzorig/pytorch/build/third_party/onnx;C:/Users/Ganzorig/pytorch/c10/cuda/../..;C:/Users/Ganzorig/pytorch/build;C:/Program Files/NVIDIA GPU Computing Toolkit/CUDA/v10.1/include;C:/Program Files/NVIDIA GPU Computing Toolkit/CUDA/v10.1/include;C:/Program Files/NVIDIA GPU Computing Toolkit/CUDA/v10.1/include;C:/Program Files/NVIDIA GPU Computing Toolkit/CUDA/v10.1\include;C:/Program Files/NVIDIA GPU Computing Toolkit/CUDA/v10.1/include
Invalid escape sequence \i
Policy CMP0010 is not set: Bad variable reference syntax is an error. Run
"cmake --help-policy CMP0010" for policy details. Use the cmake_policy
command to set the policy and suppress this warning.
This warning is for project developers. Use -Wno-dev to suppress it.
```
Compared to https://github.com/pytorch/pytorch/issues/24044 , this commit moves the fix up, and uses [bracket arguments](https://cmake.org/cmake/help/v3.12/manual/cmake-language.7.html#bracket-argument).
PR also sent to upstream: https://gitlab.kitware.com/cmake/cmake/merge_requests/3679
Pull Request resolved: https://github.com/pytorch/pytorch/pull/24420
Differential Revision: D16914193
Pulled By: ezyang
fbshipit-source-id: 9f897cf4f607502a16dbd1045f2aedcb49c38da7