Incorrect stack trace for stripped binaries

[xppt]

If the executable is stripped, I expect the FailureSignalHandler to dump module+offset for each stack frame, but the output is always (unknown).
Seems like this is because of a typo in OpenObjectFileContainingPcAndGetStartAddress.

Code to reproduce:
repro.zip
Just extract and run ./run_test.py on the host (docker and python3 are required).

Expected output

    @     0x7fa3c2b86699 __cxa_throw
    @     0x55a4ed24f389 (/build/testbin-stripped+0x2388)
    @     0x55a4ed24f3c6 main

Actual output

    @     0x7f81b4790699 __cxa_throw
    @     0x5645b9032389 (unknown)
    @     0x5645b90323c6 main

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[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 64.41%. Comparing base (c0813f9) to head (78484ce).
Report is 38 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1092      +/-   ##
==========================================
+ Coverage   63.56%   64.41%   +0.85%     
==========================================
  Files          19       19              
  Lines        2566     2563       -3     
  Branches      910      909       -1     
==========================================
+ Hits         1631     1651      +20     
+ Misses        676      647      -29     
- Partials      259      265       +6     

Files with missing lines	Coverage Δ
src/symbolize.cc	63.75% <100.00%> (+7.22%)	⬆️

... and 3 files with indirect coverage changes

[sergiud]

Thanks for the PR! I have one minor remark.

Also, what's the output with your changes?

[xppt]

Also, what's the output with your changes?

The stack trace contains module+offset line after patching:

    @     0x7fde6810f699 __cxa_throw
    @     0x55ce95d3d389 (/build/testbin-stripped+0x2388)
    @     0x55ce95d3d3c6 main

[sergiud]

Thank you!