[Ada] Delay all aspects

[Arnaud Charlet <charlet at adacore dot com>]

This patch implements delay of all aspects till the freeze point
as finally decided in the Ada 2012 design. It also corrects a
couple of errors in handling delayed aspects (now that we have
many more of them, these errors showed up).

Here is a test program (compiled with -gnatws)

     1. pragma Ada_2012;
     2. with Ada.Text_IO; use Ada.Text_IO;
     3. procedure DelayAllAspect is
     4.    Outer_X : constant Integer := 8;
     5.    Outer_Y : constant Integer := 8;
     6.
     7.    package X1 is
     8.       type X1T is range 1 .. 2 with
     9.         Size => Outer_X;
    10.       Outer_X : constant Integer := 16;
    11.    end;
    12.
    13.    package X2 is
    14.       type X2T is range 1 .. 2 with
    15.         Size => Outer_X;
    16.       V2T : X2T; -- freezes
    17.       Outer_X : constant Integer := 16;
    18.       --  Should give error!
    19.    end X2;
    20.
    21.    package X3 is
    22.       type X3T is range 1 .. 2 with
    23.         Size => Outer_X + Outer_Y;
    24.       Outer_Y : constant Integer := 24;
    25.       V3T : X3T; -- freezes
    26.       Outer_X : constant Integer := 40;
    27.       --  Should give error!
    28.    end X3;
    29.
    30. begin
    31.    Put_Line (X1.X1T'Size'Img & " should be 16");
    32.    Put_Line (X2.X2T'Size'Img & "  should be 8");
    33.    Put_Line (X3.X3T'Size'Img & " should be 32");
    34. end DelayAllAspect;

The output with this patch is:

 16 should be 16
 8  should be 8
 32 should be 32

Note the two lines marked "Should give error", These reflect
the requirement under discussion that if the freeze point is
before the end of the declarative region, and the visibility
changes between the freeze point and the end of this region,
the program is illegal.

This seems very hard to do, and we will wait on this till
(a) the final decision is to go in this direction and
(b) we figure out how the heck to implement this (sees
awfully difficult).

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

2011-08-01  Robert Dewar  <dewar@adacore.com>

	* aspects.ads (Boolean_Aspects): New subtype.
	* exp_ch13.adb (Expand_Freeze_Entity): Fix errors in handling aspects
	for derived types in cases where the parent type and derived type have
	aspects.
	* freeze.adb (Freeze_Entity): Fix problems in handling derived type
	with aspects when parent type also has aspects.
	(Freeze_Entity): Deal with delay of boolean aspects (must evaluate
	boolean expression at this point).
	* sem_ch13.adb (Analyze_Aspect_Specifications): Delay all aspects in
	accordance with final decision on the Ada 2012 feature.
	* sinfo.ads, sinfo.adb (Is_Boolean_Aspect): New flag.

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