[compiler-rt] [HWASan] Fix symbol indexing (PR #135967)

[Stefan Bossbaly via llvm-commits]

https://github.com/StefanBossbaly commented:

Implemented suggestions. Also attempting to follow [LLVM's guidance on Python source formatting](https://llvm.org/docs/CodingStandards.html#python-version-and-source-code-formatting) but it seems that `hwasan_symbolize` is not currently formatted using [PEP 8](https://peps.python.org/pep-0008/) formatting. Currently my proposed changes are not formatted.

https://github.com/llvm/llvm-project/pull/135967