[Patch, Fortran] Cleanup of gfc_extend_expr

[Janus Weil]

>> I think the patch is fine and can be committed.  But, give
>> Steven a chance to respond before committing.
>
> Thanks, Steve. I think three days should be long enough. Will commit
> later today (if no one protests in the meantime).

Committed as r181044.

Cheers,
Janus