[Ada] Make GNAT.AWK API compatible with Ada 2005.

Index: g-awk.adb
===================================================================
--- g-awk.adb	(revision 177274)
+++ g-awk.adb	(working copy)
@@ -6,7 +6,7 @@ 
 --                                                                          --
 --                                 B o d y                                  --
 --                                                                          --
---                     Copyright (C) 2000-2010, AdaCore                     --
+--                     Copyright (C) 2000-2011, AdaCore                     --
 --                                                                          --
 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
 -- terms of the  GNU General Public License as published  by the Free Soft- --
@@ -29,11 +29,6 @@ 
 --                                                                          --
 ------------------------------------------------------------------------------
 
-pragma Ada_95;
---  This is needed because the pragmas Warnings (Off) in Current_Session and
---  Default_Session (see below) do not work when compiling clients of this
---  package that instantiate generic units herein.
-
 with Ada.Exceptions;
 with Ada.Text_IO;
 with Ada.Strings.Unbounded;
@@ -735,30 +730,18 @@ 
    -- Current_Session --
    ---------------------
 
-   function Current_Session return Session_Type is
+   function Current_Session return not null access Session_Type is
    begin
-      pragma Warnings (Off);
-      return Cur_Session;
-      --  ???The above return statement violates the Ada 2005 rule forbidding
-      --  copying of limited objects (see RM-7.5(2.8/2)). When compiled with
-      --  -gnatg, the compiler gives a warning instead of an error, so we can
-      --  turn it off.
-      pragma Warnings (On);
+      return Cur_Session.Self;
    end Current_Session;
 
    ---------------------
    -- Default_Session --
    ---------------------
 
-   function Default_Session return Session_Type is
+   function Default_Session return not null access Session_Type is
    begin
-      pragma Warnings (Off);
-      return Def_Session;
-      --  ???The above return statement violates the Ada 2005 rule forbidding
-      --  copying of limited objects (see RM-7.5(2.8/2)). When compiled with
-      --  -gnatg, the compiler gives a warning instead of an error, so we can
-      --  turn it off.
-      pragma Warnings (On);
+      return Def_Session.Self;
    end Default_Session;
 
    --------------------
Index: g-awk.ads
===================================================================
--- g-awk.ads	(revision 177281)
+++ g-awk.ads	(working copy)
@@ -229,12 +229,12 @@ 
    --  Set the session to be used by default. This file will be used when the
    --  Session parameter in following services is not specified.
 
-   function Current_Session return Session_Type;
+   function Current_Session return not null access Session_Type;
    --  Returns the session used by default by all services. This is the
    --  latest session specified by Set_Current service or the session
    --  provided by default with this implementation.
 
-   function Default_Session return Session_Type;
+   function Default_Session return not null access Session_Type;
    --  Returns the default session provided by this package. Note that this is
    --  the session return by Current_Session if Set_Current has not been used.
 
@@ -633,6 +633,7 @@ 
 
    type Session_Type is new Ada.Finalization.Limited_Controlled with record
       Data : Session_Data_Access;
+      Self : not null access Session_Type := Session_Type'Unchecked_Access;
    end record;
 
    procedure Initialize (Session : in out Session_Type);