bug#50752: 28.0.50; easy-menu-define lowers the menu-bar key

[Stefan Kangas]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> it's now `pif tools' after being changed to use easy-menu-define, I
> think?  So the downcase would work fine for everybody -- except people
> that have a Turkish locale, where the downcase would yield `pıf tools',
> and we'd have no match after all.

I didn't see that we were discussing a regular "I" character (bad font
in this client), but yes that is obviously incorrect.

Do we have an alternative to downcase, or should we just ensure that
it uses a standard case-table?  Could that lead to any other problems?