[gofrtran] Fix PR 16465: accept -ffixed-line-length-72

[Billinghurst, David (CALCRTS)]

Tobias Schlüter wrote: 
> I've updated my patch. But before I post it, I want to know: Is
> support for arbitrary line lengths with --fixed-line-length-none also
> a must, or is the builtin maximum of 132 ok? I just don't want to do
> that work unnecessarily.

Tobi,

I couldn't find a way.  I tried a few fancy ways before I settled on the
very simple tests in g77.dg/ffixed-line-length-*.f.

	David