[Ada] Implementation of quantified expressions

[Arnaud Charlet <charlet at adacore dot com>]

This patch implements part of the Ada2012 quantified expressions machinery.
Iterator forms over arrays are supported.
Execution of the following in Ada2012 mode must yield:

YES
FALSE
TRUE
TRUE
TRUE

--
with Text_IO; use Text_IO;
procedure Proc is
   type Ar is array (1..10) of integer;
   Thing : Ar := (others => 0);

   function Change (X : integer) return Boolean is
   begin
      if Thing (X) >= 0 then
         Thing (X) := -1;
         return True;
      else
         return False;
      end if;
   end Change;
   
begin
   if (for all I in thing'range => Thing (I) = 0) then
      Put_Line ("YES");
   end if;

   Thing (5 ) := -111;
   Put_Line (Boolean'Image (for all J in thing'range => Thing (J) > 0));

   Put_Line (Boolean'Image (for some J in thing'range => Thing (J) < 0));

   while (for some I in thing'range => Change (I)) loop null; end loop;

   Put_Line (Boolean'Image (for all K in thing'range => Thing (K) < 0));

   Thing := (0,1,2,3,4,5,6,7,8,9);
   Put_Line (Boolean'Image (for all I in Thing'first.. Thing'last - 1=>
      Thing (I) < THing (I+1)));
end;

Tested on x86_64-pc-linux-gnu, committed on trunk

2010-10-19  Ed Schonberg  <schonberg@adacore.com>

	* exp_ch4.adb, exp_ch4.ads (Expand_Quantified_Expression): New procedure
	* exp_util.adb (Insert_Actions): Include Quantified_Expression.
	* expander.adb: Call Expand_Qualified_Expression.
	* par.adb: New procedure P_Quantified_Expression. Make
	P_Loop_Parameter_Specification global for use in quantified expressions.
	* par-ch3.adb (P_Subtype_Mark_Resync): Allow "some" as an identifier if
	version < Ada2012.
	* par-ch4.adb: New procedure P_Quantified_Expression.
	* par-ch5.adb: P_Loop_Parameter_Specification is now global.
	* scans.adb, scans.ads: Introduce token Some. For now leave as
	unreserved.
	* scn.adb (Scan_Reserved_Identifier): For earlier versions of Ada,
	treat Some as a regular identifier.
	* sem.adb: Call Analyze_Quantified_Expression.
	* sem_ch4.adb, sem_ch4.ads: New procedure Analyze_Quantified_Expression.
	* sem_ch5.adb, sem_ch5.ads: Analyze_Iteration_Scheme is public, for use
	in quantified expressions.
	* sem_res.adb: New procedure Resolve_Qualified_Expression.
	* sinfo.adb, sinfo.ads: New node N_Quantified_Expression
	* snames.ads-tmpl: New name Some.
	* sprint.adb: Output quantified_expression.

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