ada: Fix wrong finalization for double subtype of bounded vector

ada: Fix wrong finalization for double subtype of bounded vector

The special handling of temporaries created for return values and subject
to a renaming needs to be restricted to the top level, where it is needed
to prevent dangling references to the frame of the elaboration routine from
being created, because, at a lower level, the front-end may create implicit
renamings of objects as these temporaries, so a copy is not allowed.

gcc/ada/

	* gcc-interface/decl.cc (gnat_to_gnu_entity) <E_Variable>: Restrict
	the special handling of temporaries created for return values and
	subject to a renaming to the top level.