dump stack trace in FM on failure

In CrashHandler...
  - make CrashHandler a non-noop... don't know why it's disabled
  - fix bitrot since we last built it
  - update to demangle symbols on Linux too, not just Mac
  - catch SIGTRAP, which will catch SK_ABORT / SkASSERT,
    unless otherwise hooked (e.g. by a debugger)

In fm...
  - use CrashHandler
  - convert exit_with_failure to SK_ABORT so they'll also dump a trace
  - flush stdout after printing what's running

Change-Id: Ib20d0e4f442d73c28e193396dc6e85935fc58544
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/208151
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
3 files changed