[patch, fortran] Fix empty substrings when simplifying

[Jerry DeLisle]

On 03/24/2018 05:46 AM, Thomas Koenig wrote:
> Hell world,
> 
> the attached patch is fairly self-explanatory, it fixes an out-of-memory
> condition.
> 
> Regression-tested. OK for trunk?
> 

Yes, and thanks for fix.

Jerry