ada: Fix limited_with in Check_Scil; allow for <> in pp of aggregate

Check_Scil failed due to not handling a type that came from a package that was
mentioned in a limited-with clause.  Also, an aggregate with an uninitialized
component was not being pretty-printed properly.

gcc/ada/

	* pprint.adb (List_Name): Check for "Box_Present" when displaying
	a list, and emit "<>" if returns True.
	* sem_scil.adb (Check_SCIL_Node): Handle case when the type of a
	parameter is from a package that was mentioned in a limited with
	clause, and make no further checks, since this check routine does
	not have all the logic to check such a usage.