http-utils: Stop exporting an internal error quark
http-utils: Stop exporting an internal error quark

This made its way into the Debian symbols file, but looks like it was
never supposed to be exported.

Signed-off-by: Philip Withnall <29c2a2ac2a854b9cf047275aa9de346d096be2e0@endlessm.com>

flatpak/flatpak,flatpak/flatpak,flatpak/flatpak,flatpak/flatpak,flatpak/flatpak