[Patch, fortran] Use correct type for transferring array descriptor info to library

[FX Coudert]

> I plan to commit the following obvious patch in 24 hours unless  
> someone objects. The problem is that the array descriptor triplets  
> for each dimension (ubound, stride, lbound) are transferred as  
> GFC_INTEGER_4 rather than as the correct array index type  
> (typedeffed to ssize_t). It's a rather obscure bug, surfacing only  
> when doing namelist I/O on big arrays on 64-bit platforms. But it's  
> the right thing to do, so it should be done.

Do you have any ways to write a testcase that doesn't need gigabytes  
of disk space?

The patch is otherwise OK.

FX