ada: Fix handling of iterated component associations with sub-aggregates

ada: Fix handling of iterated component associations with sub-aggregates

Fix a number of problems in handling of actions generated for a
2-dimensional array aggregate where the outer aggregate has iterated
component association and the inner aggregate involves run-time checks.

gcc/ada/

	* exp_aggr.adb (Add_Loop_Actions): Actions are now attached to
	iterated component association just like they are attached to
	ordinary component association.
	(Build_Array_Aggr_Code): If resolution of the array aggregate
	generated some actions, e.g. for run-time checks, then we must
	keep them; same for the Other_Clause.
	* sem_aggr.adb (Resolve_Iterated_Component_Association): Unset
	references to iterator variable in loop actions (which might come
	from run-time check), just these references are unset in the
	expression itself.