They're not parsed since 6b22a11170
(2020), so there's no point in keeping those workarounds. They're only
kept in utility application sources as they're parsed for pages, and in
tweakable implementations where it's easier to just copypaste the whole
ifdef expression from the header every time instead of modifying it to
not include DOXYGEN_GENERATING_OUTPUT.
Vladimír Vondruš