Do not suggest updates for incompatible apps

I just found this little bug when debugging a separate issue that rendered all apps incompatible.

If you want to reproduce this, simply modify fdroidclient to think that all the apks are incompatible.

Result: https://i.imgur.com/jGN27aK.png

I think this is because we fall back to recommending the latest incompatible version if all the versions are incompatible. Which is fine - but then we need to make sure that these apps never get marked as having updates.