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/math/simplex/simplex.cpp

@@ -74,4 +74,4 @@ namespace simplex {
             }
         }
     }
-};
+}