Remove unnecessary semicolons (Attempt 2) (#10020)

This is another PR towards the goal of getting Z3 to compile cleanly
when included via FetchContents into clang-tidy, which uses a pretty
strict set of warnings.

This is a second version of https://github.com/Z3Prover/z3/pull/9957. I
address @NikolajBjorner 's comments about not changing the semicolons
after macro invocations, because some editors work better with them
present. It now, to the best of my ability, only deletes semis:

* after the closing brace of namespace decl.
* after the closing brace of an extern "C" decl.
* after a function definition.

This PR is very large, but it consists entirely of deletions of
semicolons in these situations.

(If there was a way to update the previous PR, which had been closed,
and that is preferable, please let me know. I couldn't figure it out.)

src/ast/for_each_expr.cpp

@@ -94,7 +94,7 @@ namespace has_skolem_functions_ns {
         void operator()(app const * n) const { if (n->get_decl()->is_skolem() && n->get_num_args() > 0) throw found(); }
         void operator()(quantifier * n) const {}
     };
-};
+}
 
 bool has_skolem_functions(expr * n) {
     has_skolem_functions_ns::proc p;