Fix conflict between XNNPACK's clog dependency and our cpuinfo dependency (#33922)
Summary:
Currently if we run
```bash
DEBUG=1 ONNX_ML=0 MAX_JOBS=8 CMAKE_CXX_COMPILER_LAUNCHER=ccache CMAKE_C_COMPILER_LAUNCHER=ccache CMAKE_CUDA_COMPILER_LAUNCHER=ccache USE_OPENMP=0 USE_DISTRIBUTED=0 USE_MKLDNN=0 USE_NCCL=0 USE_CUDA=1 USE_CUDNN=0 USE_STATIC_CUDNN=0 USE_NNPACK=0 USE_QNNPACK=0 USE_FBGEMM=0 BUILD_TEST=0 TORCH_CUDA_ARCH_LIST="6.1" python setup.py develop --cmake-only
```
then `touch build/CMakeCache.txt` (which adjusting build options will
do), then `python setup.py develop`, the following error message will
show up:
```
CMake Error at build/clog-source/CMakeLists.txt:249 (ADD_SUBDIRECTORY):
ADD_SUBDIRECTORY not given a binary directory but the given source
directory "/home/hong/wsrc/pytorch/build/clog-source" is not a subdirectory
of "/home/hong/wsrc/pytorch/build/clog-source". When specifying an
out-of-tree source a binary directory must be explicitly specified.
```
This is due to a conflict between our cpuinfo submodule and XNNPACK's
external clog dependency. Moving our cpuinfo upward and setting
CLOG_SOURCE_DIR resolves the issue.
---
Also reverted https://github.com/pytorch/pytorch/issues/33947 , where `CLOG_SOURCE_DIR` as an option is not quite appropriate (given that cpuinfo uses its included clog subdir) and the setting of this variable should be a bit later when the dir of cpuinfo is known.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/33922
Differential Revision: D20193572
Pulled By: ezyang
fbshipit-source-id: 7cdbdc947a6c7e0ef10df33feccb5b20e1b3ba43
