Keep ELF metadata for lld

[peppergrayxyz]

Fixes: #2978

[avagin]

please write proper commit messages: https://www.kernel.org/doc/html/v4.11/process/submitting-patches.html#describe-your-changes

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 57.31%. Comparing base (b7f6b72) to head (5d86294).
⚠️ Report is 655 commits behind head on criu-dev.

Additional details and impacted files

@@             Coverage Diff              @@
##           criu-dev    #2979      +/-   ##
============================================
- Coverage     57.76%   57.31%   -0.46%     
============================================
  Files           142      157      +15     
  Lines         37664    40277    +2613     
  Branches          0     8831    +8831     
============================================
+ Hits          21758    23085    +1327     
- Misses        15906    16985    +1079     
- Partials          0      207     +207     

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