message: doc: add comment about getting symbolized asan backtraces
diff: @@ -230,7 +230,9 @@ To build and run tests with the gcc compiler's [address sanitizer
  bazel test -c dbg --config=asan //test/...
  ```
  -The ASAN failure stack traces include line numbers as a result of running ASAN with a `dbg` build above.
  +The ASAN failure stack traces include line numbers as a result of running ASAN with a `dbg` build above. If the
  +stack trace is not symbolized, try setting the ASAN_SYMBOLIZER_PATH environment variable to point to the
  +llvm-symbolizer binary (or make sure the llvm-symbolizer is in your $PATH).
  If you have clang-5.0 or newer, additional checks are provided with:
  