https://github.com/openjdk/jfx/pull/1789 introduced LOG macro which uses variadic arguments. This enhancement is a cleanup one, to track updating the rest of numbered LOG/ERROR macros in GTK Glass backend with the new variadic versions. Some spots directly use `fprintf(stderr, ...)` instead of using LOG/ERROR macros, those should also be adjusted. LOG/ERROR macros could also print file name and line to easier identify where potential problems arise.