Support C17, C23 standards with goto-cc

[tautschnig]

We previously added the necessary language features in the C front end, but failed to permit selection of these standards in goto-cc.

Also, GCC >= 11 and Clang >= 17 support C23-style attributes irrespective of the configured language standard. So let's accept these in our C front end whenever operating in GCC/Clang mode.

Fixes: #8671

• 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.

[codecov]

Codecov Report

Attention: Patch coverage is 69.23077% with 4 lines in your changes missing coverage. Please review.

Project coverage is 80.39%. Comparing base (e88ed5f) to head (fbb9502).
Report is 2 commits behind head on develop.

Files with missing lines	Patch %	Lines
src/ansi-c/scanner.l	40.00%	3 Missing ⚠️
src/goto-cc/gcc_mode.cpp	87.50%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #8673   +/-   ##
========================================
  Coverage    80.39%   80.39%           
========================================
  Files         1688     1688           
  Lines       207387   207399   +12     
  Branches        73       73           
========================================
+ Hits        166728   166747   +19     
+ Misses       40659    40652    -7     

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[archigup]

Tested and works for me.
Shouldn't the closes be #8671 and not #8617?

[tautschnig]

Tested and works for me. Shouldn't the closes be #8671 and not #8617?

Thank you for catching that!