[Ada] Enable literal aspect specifications in Big_Numbers specs

[Pierre-Marie de Rodat]

Specify the Integer_Literal aspect for the type
Ada.Numerics.Big_Numbers.Big_Integers.Big_Integer.  Specify the
Real_Literal aspect for the type
Ada.Numerics.Big_Numbers.Big_Reals.Big_Real.

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

2020-06-16  Steve Baird  <ba...@adacore.com>

gcc/ada/

        * libgnat/a-nbnbin.ads, libgnat/a-nbnbre.ads: Uncomment the
        commented-out Integer_Literal aspect specification for type
        Big_Integer.
--- gcc/ada/libgnat/a-nbnbin.ads
+++ gcc/ada/libgnat/a-nbnbin.ads
@@ -27,8 +27,8 @@ package Ada.Numerics.Big_Numbers.Big_Integers
   with Preelaborate
 is
    type Big_Integer is private with
-   --  Integer_Literal => From_String,
-     Put_Image => Put_Image;
+     Integer_Literal => From_String,
+     Put_Image       => Put_Image;
 
    function Is_Valid (Arg : Big_Integer) return Boolean
      with Convention => Intrinsic;

--- gcc/ada/libgnat/a-nbnbre.ads
+++ gcc/ada/libgnat/a-nbnbre.ads
@@ -26,7 +26,7 @@ package Ada.Numerics.Big_Numbers.Big_Reals
   with Preelaborate
 is
    type Big_Real is private with
---    Real_Literal => From_String,
+     Real_Literal => From_String,
      Put_Image    => Put_Image;
 
    function Is_Valid (Arg : Big_Real) return Boolean