simpleperf: report unwinding failures.

1. When --log debug is used, store unwinding results in
   UnwindingResultRecords in perf.data.
2. Use unwinding_result_reporter.py to report unwinding results.

This is to help finding different unwinding failures.

Bug: http://b/69383534
Test: run simpleperf_unit_test.
Test: run unwinding_result_reporter.py manually.
Change-Id: I6d7f107e9758b1ec55ed35b49657bb41d47e2178
11 files changed