[Ada] Fix handling of boolean aspects

[Arnaud Charlet <charlet at adacore dot com>]

This patch fixes boolean aspects in two respects, first
there is no delay in evaluation of the arguments. The
following compiles clean and executes quietly in -gnata
mode.

     1. pragma Ada_2012;
     2. procedure baspect1 is
     3.    type X is array (0 .. 31) of Boolean with
     4.      Pack => True;
     5.    True : constant Boolean := False;
     6. begin
     7.    pragma Assert (X'Size = 32);
     8. end;

Second, it is no longer allowed to cancel inherited
aspects on derived types, as shown by this example:

     1. pragma Ada_2012;
     2. package baspect2 is
     3.    type P is array (0 .. 31) of Boolean with
     4.      Pack => True;
     5.    type U is array (0 .. 31) of Boolean with
     6.      Pack => False;
     7.    type DP1 is new P with
     8.      Pack => True;        -- OK
     9.    type DU1 is new U with
    10.      Pack => False;       -- OK
    11.    type DP2 is new P with
    12.      Pack => False;       -- ERROR
                     |
        >>> derived type "DP2" inherits aspect "pack", cannot cancel

    13.    type DU2 is new U with
    14.      Pack => True;        -- OK
    15. end;

In addition, the calling sequence of Analyze_Aspect_Specification
is changed to improve performance efficiency (some slow down in
compilation time was noticed from the previous implementation).

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

2011-08-02  Robert Dewar  <dewar@adacore.com>

	* sem_ch12.adb, sem_ch11.adb: New calling sequence for
	Analyze_Aspect_Specifications
	* sem_ch13.adb
	(Analyze_Aspect_Specifications): New handling for boolean aspects
	* sem_ch13.ads (Analyze_Aspect_Specifications): New calling sequence
	* sem_ch3.adb, sem_ch6.adb, sem_ch7.adb, sem_ch9.adb: New calling
	sequence for Analyze_Aspect_Specifications
	* sem_prag.adb (Analyze_Pragma): Remove use of Aspect_Cancel entirely
	* sinfo.ads, sinfo.adb (Aspect_Cancel): Remove, no longer used

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