ada: Emit more warnings on unsupported overlay

ada: Emit more warnings on unsupported overlay

In the case where the overlaid object is nested in a record or is an
array element as in:

    for Foo'Address use Item.Nested_Item'Address;
or  for Foo'Address use Item (Bar)'Address;

the compiler was not emitting a warning in case of differing
Scalar_Storage_Order values.

gcc/ada/ChangeLog:

	* sem_util.adb (Find_Overlaid_Entity): Add extra parameter to
	extract the type being overlaid.
	(Note_Possible_Modification): Adjust call to Find_Overlaid_Entity.
	(Ultimate_Overlaid_Entity): Likewise.
	* sem_ch13.adb (Analyze_Attribute_Definition_Clause): Likewise.
	* sem_util.ads (Find_Overlaid_Entity): Add extra parameter to
	extract the type being overlaid.
	* freeze.adb (Check_Address_Clause): Likewise.