ada: Fix premature finalization of temporaries for interface objects

ada: Fix premature finalization of temporaries for interface objects

This restores the proper finalization of temporaries for interface objects
in the case where the initializing expression is not of an interface type.

It turns out that neither Is_Temporary_For_Interface_Object nor its previous
incarnation are sufficient to catch all the various cases, so it is replaced
by a small enhancement to Is_Aliased, which is more robust.

gcc/ada/

	* exp_util.adb (Is_Temporary_For_Interface_Object): Delete.
	(Is_Finalizable_Transient.Is_Aliased): Deal with the specific case
	of temporaries generated for interface objects.