Detection of stdio.h in gmp.h

[Kevin Ryde]

Patrick Pelissier <Patrick.Pelissier at loria.fr> writes:
>
>   It appears for me to be a hack. On some systems, it may not work,
> and it may change in the future.

When it fails it's not the end of the world, you merely miss out of
prototypes involving FILE.

>   EOF should be defined only in stdio.h,

Hopefully.

> and it is a standard constante, no?

Yep.

I don't know why that hasn't been done.  That stuff dates right back
to gmp 1, in various forms.  Maybe Torbjorn can remember the
motivation.