[patch, Fortran] Fix PR 119049 and 119074, external prototypes with different arglists

[Thomas Koenig]

Hi Andre,

> while the patch looks ok to me, why did you not choose to generate a "22.7.2
> Variable-Length Parameter Lists"
> 
> https://www.gnu.org/software/c-intro-and-ref/manual/html_node/Variable-Number-of-Arguments.html
> 
> when the arguments differ? Then its the callee responsibility to figure
> stuff out. Just out of curiosity. Is this prohibited by any standard? My
> question is just out of interest. No need to change the patch. Having a warning
> is better, then running into "WTF?".

A variable-length parameter list is something that the caller and
the callee must agree on, otherwise this can (and will) cause breakage
on many ABIs - aarch64 and Power among them. x86_64 is an exception,
there it is mostly harmless.

> Look good to me, ok for mainline.

Committed as r15-7817-g21ca9153ebe525b077ac96811cfd48be6b259e7e .

Thanks for the review!

I will mention the new option in changes.html shortly.

Best regards

	Thomas