re: include: Add ONCE macro for making debug output less noisy

[Dan Kegel]

Alexandre wrote:
> > +#define WINE_ONCE(do_once) ...
>
> I don't think that buys anything over spelling it out explicitly.

It makes it easier to grep for, which might be useful if you
want to find all the places it's used to throttle messages
that shouldn't be happening in the first place.