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

[ndame]

>
> read-char-choice is a generalisation (sort of) of `y-or-n-p', which does show 
> the cursor. (And I checked with 25.1 -- it shows the cursor there, too.) So 
> if we're going to make things consistent,


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?")