Invoke functions marked __attribute__((destructor))

[tautschnig]

This is a GCC extension that our front-end parses, but an implementation
of the desired semantics was hitherto missing.

• Each commit message has a non-empty body, explaining why the change was made.
• n/a Methods or procedures I have added are documented, following the guidelines provided in CODING_STANDARD.md.
• n/a The feature or user visible behaviour I have added or modified has been documented in the User Guide in doc/cprover-manual/
• Regression or unit tests are included, or existing tests cover the modified code (in this case I have detailed which ones those are in the commit message).
• n/a My commit message includes data points confirming performance improvements (if claimed).
• My PR is restricted to a single feature or bugfix.
• n/a White-space or formatting changes outside the feature-related changed lines are in commits of their own.

[chrisr-diffblue]

Looks sensible to me. A couple of sanity queries, and tiny optional nit picks. Nothing to block the PR.

[tautschnig]

Looks sensible to me. A couple of sanity queries, and tiny optional nit picks. Nothing to block the PR.

Thank you for all the helpful comments. All suggestions implemented.

[codecov]

Codecov Report

Merging #6603 (0319333) into develop (5aae9d0) will increase coverage by 0.00%.
The diff coverage is 91.89%.

@@           Coverage Diff            @@
##           develop    #6603   +/-   ##
========================================
  Coverage    76.49%   76.50%           
========================================
  Files         1578     1578           
  Lines       181464   181475   +11     
========================================
+ Hits        138816   138833   +17     
+ Misses       42648    42642    -6     

Impacted Files	Coverage Δ
src/solvers/lowering/byte_operators.cpp	92.17% <76.92%> (ø)
src/ansi-c/ansi_c_convert_type.cpp	79.42% <100.00%> (+0.23%)	⬆️
src/ansi-c/ansi_c_entry_point.cpp	88.65% <100.00%> (+0.54%)	⬆️
src/ansi-c/c_storage_spec.cpp	97.56% <100.00%> (ø)
src/ansi-c/parser.y	79.70% <100.00%> (+0.06%)	⬆️
src/util/c_types.h	100.00% <100.00%> (ø)
src/util/pointer_expr.h	78.77% <100.00%> (ø)
src/util/std_types.cpp	85.86% <100.00%> (ø)
src/util/std_types.h	95.77% <100.00%> (ø)
src/util/type.h	100.00% <100.00%> (ø)
... and 11 more

---

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