ada: Small fixes to handling of private views in instances

ada: Small fixes to handling of private views in instances

The main change is the removal of the special bypass for private views in
Resolve_Implicit_Dereference, which in exchange requires additional work
in Check_Generic_Actuals and a couple more calls to Set_Global_Type in
Save_References_In_Identifier.  This also removes an unused parameter in
Convert_View and adds a missing comment in Build_Derived_Record_Type.

gcc/ada/

	* exp_ch7.adb (Convert_View): Remove Ind parameter and adjust.
	* sem_ch12.adb (Check_Generic_Actuals): Check the type of both in
	and in out actual objects, as well as the type of formal parameters
	of actual subprograms.  Extend the condition under which the views
	are swapped to nested generic constructs.
	(Save_References_In_Identifier): Call Set_Global_Type on a global
	identifier rewritten as an explicit dereference, either directly
	or after having first been rewritten as a function call.
	(Save_References_In_Operator): Set N2 unconditionally and reuse it.
	* sem_ch3.adb (Build_Derived_Record_Type): Add missing comment.
	* sem_res.adb (Resolve_Implicit_Dereference): Remove special bypass
	for private views in instances.