Remainder of xdvik C23 fixes

[Sam James]

Karl Berry <karl at freefriends.org> writes:

> Hi Sam - I installed the patches (r72980). Thanks.

Hi Karl,

Thank you as usual!

>
> BTW, for the future, it is helpful to also provide ChangeLog entries.

Ack -- sorry, I try to keep in mind which projects need it, and forgot
TeX likes them. Will do next time!

>     
>     C23 removes unprotoyped functions and `void foo();` now means `voo
>     foid(void);` rather than "any arguments". 
>
> The lack of concern for backward compatibility by standards committees
> is discouraging. Anyway. -k

thanks,
sam