ada: Adjust again the implementation of storage models
The code generator must now be prepared to translate assignment statements
to objects allocated with a storage model and that are not initialized yet.
gcc/ada/
* gcc-interface/trans.cc (Attribute_to_gnu) <Attr_Size>: Tweak.
(gnat_to_gnu) <N_Assignment_Statement>: Declare a local variable.
For a target with a storage model, use the Actual_Designated_Subtype
to compute the size if it is present.