[patch, fortran] Fix PR 90813

[Thomas Koenig]

Hi Paul,

> That is very well done. Thanks for picking it up and running with it.
> OK on both the fix and the dumping of the gsymbols.

Committed, thanks.

> You might consider back porting both this patch and my fix for the
> original bug to 9-branch.

Both patches apply cleanly together on gcc-9 (well, except for the
whitespace fix of a comment that didn't exist yet in gcc-9, so
I think we can ignore than), and pass regression-tests on POWER9.

So, I will commit this tonight.

Regards

	Thomas