[patch, Fortran] Fix PR 60526, variable name has already been declared as a type

[Thomas Koenig]

Hi Janne,

[std::string]

> As we're supposed to be C++ nowadays, why aren't we
> using that?

My reason is simple: I know C and Fortran. I hardly know C++,
and I don't want to learn it for the sake of some largely
irrelevant micro-optimizations.

We should restrict C++ usage to those cases where there is
a clear and large benefit.

Regards

	Thomas