Disable /fix/ updates.

This will shut up a fake error because M+ can't parse 404 messages.

Assuming we have no plan to override what a server provides, this is appropriate. /fix/ has been stale since 2016~ish on official ManaPlus, and was never used by ManaVerse.

Keep in mind that this only toggles it off ─ I didn't remove any code whatsoever so if there's anything in /fix/ which you got from ManaPlus it'll still be parsed.