Use JSON format of llvm-symbolizer

The LLVM webpage of llvm-symbolizer[1] demonstrates outputs in JSON
format as the machine readable format.

[1]: https://llvm.org/docs/CommandGuide/llvm-symbolizer.html

Bug: None
Test: stack with a local stack trace
Test: python3 symbol.py
Change-Id: Iee6b8805510f5f8569b0a454849fc2e4ffb6d510
1 file changed