ada: Remove Max_Entry_Queue_Depth pragma/aspect

ada: Remove Max_Entry_Queue_Depth pragma/aspect

It was implemented apparently because a very early version of AI12-0164
that standardizes GNAT's Max_Queue_Length opted for the subtly different
moniker, but later versions of the AI use Max_Entry_Queue_Length instead.

gcc/ada/

	* aspects.ads (Aspect_Id): Remove Aspect_Max_Entry_Queue_Depth.
	(global arrays): Remove entry for it.
	* exp_ch9.adb (Expand_N_Protected_Type_Declaration): Remove
	reference to pragma Max_Entry_Queue_Depth in comment.
	* par-prag.adb (Prag): Remove handling of
	Pragma_Max_Entry_Queue_Depth.
	* sem_ch13.adb (Analyze_Aspect_Specifications): Remove reference
	to aspect Max_Entry_Queue_Depth in comment.
	(Analyze_Aspect_Specifications): Remove processing of aspect
	Max_Entry_Queue_Depth.
	(Check_Aspect_At_Freeze_Point): Likewise.
	* sem_prag.ads (Find_Related_Declaration_Or_Body): Remove
	reference to pragma Max_Entry_Queue_Depth in comment.
	* sem_prag.adb (Analyze_Pragma): Remove processing of pragma
	Max_Entry_Queue_Depth.
	(Sig_Flags): Remove entry for Pragma_Max_Entry_Queue_Depth.
	* sem_util.adb (Get_Max_Queue_Length): Remove handling of pragma
	Max_Entry_Queue_Depth.
	(Has_Max_Queue_Length): Likewise.
	* snames.ads-tmpl (Name_Max_Entry_Queue_Depth): Move back from
	pragmas section to others section.
	(Pragma_Id): Remove Pragma_Max_Entry_Queue_Depth.