[Patch, Fortran] CLASS handling for assumed-rank arrays

[Tobias Burnus]

This patch assumes that the basic assumed-rank support is included, 
http://gcc.gnu.org/ml/fortran/2012-06/msg00144.html

The attached patch implements the support of passing non-assumed-rank 
type/class arrays to assumed-rank class/type dummy arguments (type was 
working before). And passing assumed-rank class arrays to assumed-rank 
class arrays. It does not support passing assumed-rank class arrays to 
type arrays.

The problem with the latter is that gfortran uses the TYPE_SIZE_UNIT to 
access the array elements, which imlies a copy in/copy out. For 
arguments with descriptor, a better choice would be to use the stride 
multiplier. (Catch: The current descriptor doesn't have one.) As the 
scalarizer doesn't work for assumed-rank arrays, the copy-in/copy-out 
fails at run time.

(See also http://j3-fortran.org/pipermail/j3/2012-June/005438.html for 
the fun with pointer association when passing a  CLASS with TARGET to a 
TYPE with TARGET.)

Additionally, I think that this patch makes gfortran the second front 
end  (after Ada), which uses a range for the assignment: I do not 
iterate through for dim, but use a.dim[1:rank] = b.dim[1:rank] in the 
assignment. The reason that I have to do a component wise assignment is 
that the class container directly contains the descriptor as a component 
- not as pointer. Thus, the descriptors can have different ranks...

Build and regtested on x86-64-linux.
OK for the trunk?

Tobias
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