bug#51475: read-char-choice should hide the cursor

[Gregory Heytings]

> As for consistency, it's strange that read-char-choice shows a static 
> cursor, while y-or-no-p shows a blinking one:
>
> (read-char-choice " a - good; b - bad; c - ugly: " '(?a ?b ?c))
>
> (y-or-n-p "How would you fix Emacs?")

That's probably because of one of your customizations, in emacs -Q both 
show a blinking cursor.