[patch, libfortran] Fix for PR 21480 (yet another complex reshape failure)

[Tobias Schlüter]

Thomas Koenig wrote:
> This fixes PR 21480.
> 
> Regression-tested on mainline.  OK, also for 4.0 when it reopens?

Yes.  If you find more of this, consider those patches obvious.

Thanks,
- Tobi