[Patch, Fortran] PR57991 - add alias warning for intent(out)/intent(out)

[Thomas Koenig]

Hi Tobias,

> Passing the same argument to nonpointer dummy arguments is only
> permitted if one does not modify the values.
>
> gfortran was warning for intent(in)/intent(out) and for OUT/IN but not
> for OUT/OUT. This patch now also warns for the latter.
>
> Build and regtested on x86-64-gnu-linux.
> OK for the trunk?

OK (obvious really).

Thanks for the patch!

	Thomas