[pytorch] update code analyzer build.sh to handle srcs with same name (#32525)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/32525
Before calling static code analyzer we need link all bitcode files into
a single module. Current approach is a bit hacky: cmake still calls "ar"
to pack bitcode files into archives, then we manually unpack these
archives and call llvm-link.
Turns out libtorch_cpu.a contains a few files with same name, e.g.:
```
aten/src/ATen/native/SoftMax.cpp
aten/src/ATen/native/mkldnn/SoftMax.cpp
```
"ar x" will only keep one of them and cause inaccurate analysis result.
Use this temporary hack to workaround the problem. Ideally should merge
this step into cmake (e.g. directly calling llvm-link to produce target
output?).
Differential Revision: D19530533
Pulled By: ljk53
fbshipit-source-id: 94b292c241abaaa0ff4a23059882abdc3522971e
