Crangler: support semicolon in post-declarator expressions

[tautschnig]

assigns clauses used in contracts use semicolons to delimit expressions.
Make sure crangler just accepts whatever occurs between matching pairs
of parentheses.

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• 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

Merging #6986 (150a826) into develop (09e1041) will increase coverage by 0.00%.
The diff coverage is 81.63%.

@@            Coverage Diff            @@
##           develop    #6986    +/-   ##
=========================================
  Coverage    77.81%   77.82%            
=========================================
  Files         1570     1569     -1     
  Lines       180682   180554   -128     
=========================================
- Hits        140601   140512    -89     
+ Misses       40081    40042    -39     

Impacted Files	Coverage Δ
src/linking/linking.cpp	59.36% <68.96%> (+0.65%)	⬆️
src/analyses/does_remove_const.cpp	100.00% <100.00%> (ø)
src/crangler/mini_c_parser.cpp	72.58% <100.00%> (+1.55%)	⬆️
src/goto-instrument/replace_calls.cpp	89.70% <100.00%> (-0.15%)	⬇️
src/goto-programs/goto_program.cpp	81.80% <100.00%> (ø)
src/goto-programs/remove_function_pointers.cpp	92.79% <100.00%> (ø)
...nalyses/does_remove_const/does_expr_lose_const.cpp	100.00% <100.00%> (ø)
...ove_const/does_type_preserve_const_correctness.cpp	100.00% <100.00%> (ø)
...does_remove_const/is_type_at_least_as_const_as.cpp	100.00% <100.00%> (ø)
... and 2 more

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[kroening]

We may wish to generalise this to a "matched parentheses consumer", which could then also eat [ ], { }.

[tautschnig]

We may wish to generalise this to a "matched parentheses consumer", which could then also eat [ ], { }.

I can see that this might make sense in a more general context, if that's what you want me to implement? In the specific case, curly braces should not play that role (for they are the start of the body), and square brackets don't seem to be necessary at the moment.