Make ansi_c_internal_additions independent of the parser object

[tautschnig]

Thread through a Boolean flag rather than relying on the parser object far away from the actual parser.

• Each commit message has a non-empty body, explaining why the change was made.
• 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.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (69bb2b6) 79.09% compared to head (6d4e0db) 79.09%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #8133      +/-   ##
===========================================
- Coverage    79.09%   79.09%   -0.01%     
===========================================
  Files         1695     1695              
  Lines       196583   196588       +5     
===========================================
+ Hits        155496   155498       +2     
- Misses       41087    41090       +3     

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