Redirect print messages to `stderr` in `torch.utils.cpp_extension` (#82097)
### Description
<!-- What did you change and why was it needed? -->
Listed in the commit message:
> The user may want to use `python3 -c "..."` to get the torch library
> path and the include path. Printing messages to stdout will mess up
> the output.
I'm using the command:
```bash
LIBTORCH_PATH="$(
python3 -c 'print(":".join(__import__("torch.utils.cpp_extension", fromlist=[None]).library_paths()))'
)"
export LD_LIBRARY_PATH="${LIBTORCH_PATH}${LD_LIBRARY_PATH:+:${LD_LIBRARY_PATH}}"
```
To let the command line tools find the torch shared libraries. I think this would be a common use case for users who writing C/C++ extensions.
I got:
```console
$ LIBTORCH_PATH="$(python3 -c 'print(":".join(__import__("torch.utils.cpp_extension", fromlist=[None]).library_paths()))')"
$ export LD_LIBRARY_PATH="${LIBTORCH_PATH}${LD_LIBRARY_PATH:+:${LD_LIBRARY_PATH}}"
$ echo "LD_LIBRARY_PATH=${LD_LIBRARY_PATH}"
LD_LIBRARY_PATH=No CUDA runtime is found, using CUDA_HOME='/usr/local/cuda-11.6'
/opt/hostedtoolcache/Python/3.7.13/x64/lib/python3.7/site-packages/torch/lib:/usr/local/cuda-11.6/lib64:
$ ls -alh "${LIBTORCH_PATH}"
ls: cannot access 'No CUDA runtime is found, using CUDA_HOME='\''/usr/local/cuda-11.6'\'''$'\n''/opt/hostedtoolcache/Python/3.7.13/x64/lib/python3.7/site-packages/torch/lib': No such file or directory
```
This PR prints messages in `torch.utils.cpp_extension` to `stderr`, which allows users to get correct result using `VAR="$(python3 -c '...')"`
### Issue
<!-- Link to Issue ticket or RFP -->
N/A
### Testing
<!-- How did you test your change? -->
N/A
Pull Request resolved: https://github.com/pytorch/pytorch/pull/82097
Approved by: https://github.com/ezyang
