ada: Use the address type of a Storage_Model_Type for 'Address

ada: Use the address type of a Storage_Model_Type for 'Address

When an Address attribute applies to an object that is a dereference of
an access value whose type has aspect Designated_Storage_Model, the
attribute will now be treated as having the address type associated
with the Storage_Model_Type of the access type's associated Storage_Model
object instead of being of type System.Address.

gcc/ada/

	* sem_attr.adb (Analyze_Attribute, Attribute_Address): In the case
	where the attribute's prefix is a dereference of a value of an
	access type that has aspect Designated_Storage_Model (or a
	renaming of such a dereference), set the attribute's type to the
	corresponding Storage_Model_Type's associated address type rather
	than System.Address.