[Ada] Warn on 'in out' param containing access in predefined private type

[Ada] Warn on 'in out' param containing access in predefined private type

gcc/ada/

	* sem_util.adb, sem_util.ads (Has_Access_Values): New formal
	Include_Internal to indicate whether internal types should be
	included.
	* sem_warn.adb (Check_References): Change E_Out_Parameter to
	Formal_Kind, to match the comment about Spec_Entity.  Pass
	Include_Internal => False to Has_Access_Values, so that we warn
	on types with access values that happen to be in internal types,
	such as Unbounded_String.
	* sem_attr.adb (Attribute_Has_Access_Values): Pass
	Include_Internal => True to Has_Access_Values, to preserve
	existing behavior.
	* libgnat/g-rewdat.adb (Do_Output): Change B from 'in out' to
	'in', to avoid warning enabled by the change to sem_warn.adb.
	* libgnat/s-objrea.adb (Check_Read_Offset): Change S from 'in
	out' to 'in', to avoid warning enabled by the change to
	sem_warn.adb.