[Ada] AI12-0307: uniform resolution rules for aggregates

[Ada] AI12-0307: uniform resolution rules for aggregates

gcc/ada/

	* sem_util.ads, sem_util.adb (Check_Ambiguous_Aggregate): When a
	subprogram call is found to be ambiguous, check whether
	ambiguity is caused by an aggregate actual.  and indicate that
	it should carry a type qualification.
	* sem_ch4.adb (Traverse_Hoonyms, Try_Primitive_Operation): Call
	it.
	* sem_res.adb (Report_Ambiguous_Argument): Call it.