[Ada] Reimplementation of accessibility checking

[Ada] Reimplementation of accessibility checking

gcc/ada/

	* checks.adb (Apply_Accessibility_Check): Modify condition to
	avoid flawed optimization and use Get_Accessibility over
	Extra_Accessibility.
	* exp_attr.adb: Remove inclusion of Exp_Ch2.adb.
	* exp_ch2.adb, exp_ch2.ads (Param_Entity): Moved to sem_util.
	* exp_ch3.ads (Init_Proc_Level_Formal): New function.
	* exp_ch3.adb (Build_Init_Procedure): Add extra accessibility
	formal for init procs when the associated type is a limited
	record.
	(Build_Initialization_Call): Add condition to handle propagation
	of the new extra accessibility paramter actual needed for init
	procs.
	(Init_Proc_Level_Formal): Created to fetch a the extra
	accessibility parameter associated with init procs if one
	exists.
	* exp_ch4.adb (Build_Attribute_Reference): Modify static check
	to be dynamic.
	* exp_ch6.adb (Add_Cond_Expression_Extra_Actual): Move logic
	used to expand conditional expressions used as actuals for
	anonymous access formals.
	(Expand_Call_Helper): Remove extranious accessibility
	calculation logic.
	* exp_util.adb: Remove inclusion of Exp_Ch2.adb.
	* par-ch3.adb (P_Array_Type_Definition): Properly set
	Aliased_Present on access definitions
	* sem_attr.adb (Resolve_Attribute): Replace instances for
	Object_Access_Level with Static_Accessibility_Level.
	* sem_ch13.adb (Storage_Pool): Replace instances for
	Object_Access_Level with Static_Accessibility_Level.
	* sem_ch6.adb (Check_Return_Construct_Accessibility): Replace
	instances for Object_Access_Level with
	Static_Accessibility_Level.
	* sem_ch9.adb (Analyze_Requeue): Replace instances for
	Object_Access_Level with Static_Accessibility_Level.
	* sem_res.adb (Check_Aliased_Parameter,
	Check_Allocator_Discrim_Accessibility, Valid_Conversion):
	Replace instances for Object_Access_Level with
	Static_Accessibility_Level.
	* sem_util.adb, sem_util.ads (Accessibility_Level_Helper):
	Created to centralize calculation of accessibility levels.
	(Build_Component_Subtype): Replace instances for
	Object_Access_Level with Static_Accessibility_Level.
	(Defining_Entity): Add extra parameter to dictate whether an
	error is raised or empty is return in the case of an irrelevant
	N.
	(Dynamic_Accessibility_Level): Rewritten to use
	Accessibility_Level_Helper.
	(Is_View_Conversion): Check membership against Etype to capture
	nodes like explicit dereferences which have types but are not
	expanded names or identifers.
	(Object_Access_LeveL): Removed.
	(Param_Entity): Moved from sem_util.
	(Static_Accessibility_Level): Created as a replacement to
	Object_Access_Level, it also uses Accessibility_Level_Helper for
	its implementation.
	* snames.ads-tmpl: Added new name for extra accessibility
	parameter in init procs.