Cleanup additional GCC warnings

When turning on the following flags, several additional warnings
were generated, which have been cleaned up in this patch. The
flags included:

-Wextra
-Wpedantic
-Wconversion
-Wsign-conversion
-Wctor-dtor-privacy
-Wshadow
-Wnon-virtual-dtor
-Wold-style-cast
-Wcast-align
-Woverloaded-virtual

tests/utils_tests.cpp

@@ -67,7 +67,7 @@ SUITE(utils_tests)
     }
 
     int j = 0;
-    void g() { j += 1; };
+    void g() { j += 1; }
     TEST(finally_function_ptr)
     {
         j = 0;