[gfortran] add ISATTY and TTYNAM intrinsics

[Tobias.Schlueter@Physik.Uni-Muenchen.DE]

Quoting FX Coudert <fxcoudert@gmail.com>:

> >> I'd
> >> suggest changing the unit argument to type int *, changing the resolution
> to
> >> convert the argument to use gfc_c_int_kind, and changing the other
> >> implementation functions accordingly.
> >
> > I still think this would be the right way to go.
>
> Well, why not? What about the new version attached?

Ok.

Thanks,
- Tobi