gtk-doc: Add all missing symbols to flatpak.sections
gtk-doc: Add all missing symbols to flatpak.sections

Closes: #1797
Approved by: alexlarsson

matthiasclasen/flatpak,flatpak/flatpak,matthiasclasen/flatpak,matthiasclasen/flatpak,flatpak/flatpak,matthiasclasen/flatpak,flatpak/flatpak,flatpak/flatpak,matthiasclasen/flatpak,flatpak/flatpak