Work around further spurious GCC12 maybe-uninitialized warnings

[tautschnig]

It seems that each GCC version introduces a new spurious case.

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• 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).
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[codecov]

Codecov Report

Patch coverage: 100.00% and project coverage change: +0.56 🎉

Comparison is base (6a689f3) 78.05% compared to head (bd66325) 78.61%.

❗ Current head bd66325 differs from pull request most recent head 85cb526. Consider uploading reports for the commit 85cb526 to get more accurate results

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #7797      +/-   ##
===========================================
+ Coverage    78.05%   78.61%   +0.56%     
===========================================
  Files         1697     1697              
  Lines       193627   193636       +9     
===========================================
+ Hits        151144   152236    +1092     
+ Misses       42483    41400    -1083     

Impacted Files	Coverage Δ
src/util/simplify_expr_int.cpp	88.55% <ø> (+6.69%)	⬆️
src/goto-instrument/unwindset.cpp	86.60% <100.00%> (+0.75%)	⬆️
src/util/cmdline.cpp	94.53% <100.00%> (+0.09%)	⬆️

... and 54 files with indirect coverage changes

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