[PyTorch][tools] Add linux64 clang-format hash
Summary:
This commit adds a reference hash for the linux64 clang-format binary and in
doing so, enables this script to be used on Linux machines.
Test Plan:
Ran the script.
```
meghanl@devvm1517:caffe2 (ff25240c|remote/master)$ export http_proxy=fwdproxy:8080
meghanl@devvm1517:caffe2 (ff25240c|remote/master)$ export https_proxy=fwdproxy:8080
meghanl@devvm1517:caffe2 (ff25240c|remote/master)$ python3 ./tools/clang_format_new.py --diff
Downloading clang-format to /data/users/meghanl/fbsource/fbcode/caffe2/.clang-format-bin
0% |################################################################| 100%
Using clang-format located at /data/users/meghanl/fbsource/fbcode/caffe2/.clang-format-bin/clang-format
meghanl@devvm1517:caffe2 (ff25240c|remote/master)$ echo $?
1
```
A non-zero return code indicates that `clang-format` will make changes.
Reviewed By: suo
Differential Revision: D20434291
fbshipit-source-id: fa13766e9d94720d4b0d8a540d2f1507e788f7a5
