[patch, fortran] Fix PR 88871

[Thomas Koenig]

Am 17.01.19 um 07:30 schrieb Thomas Koenig:
> 
> No test case because, well - it did show up on a few systems, so we will
> notice if it regresses. OK for trunk?

Both Dominique and Jürgen confirmed that it fixes the PR.

I will commit this tomorrow unless there are any objections - I'd
like to get this out of the way.

Regards

	Thomas