document-portal: Keep track of outstanding kernel refs
document-portal: Keep track of outstanding kernel refs

The kernel implicitly forgets all its inode refs when the filesystem
is unmounted, so we keep track of them explicitly so that we can
ensure we can shutdown without inode leaks.

matthiasclasen/xdg-desktop-portal,flatpak/xdg-desktop-portal,matthiasclasen/xdg-desktop-portal,matthiasclasen/xdg-desktop-portal,flatpak/xdg-desktop-portal,matthiasclasen/xdg-desktop-portal,matthiasclasen/xdg-desktop-portal,flatpak/xdg-desktop-portal,flatpak/xdg-desktop-portal