[Ada] Inconsistent scope chain due to quantified expression

[Pierre-Marie de Rodat]

Routine Build_DIC_Procedure_Declaration appears to be heavily inspired
by Build_Invariant_Procedure_Declaration; they both wrap an expression
attached to a type inside an internal procedure. Initially none of them
were calling Set_Last_Entity.

For Build_Invariant_Procedure_Declaration this was fixed previously.
For Build_DIC_Procedure_Declaration this is fixed here.

The issue affects the GNATprove tool and is not visible to end users of
the GNAT compiler. No simple test is available because this would
require a debug session.

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

2019-08-20  Piotr Trojanek  <troja...@adacore.com>

gcc/ada/

        * exp_util.adb (Build_DIC_Procedure_Declaration): Set the last
        entity of the generated Default_Initial_Condition procedure in
        order to construct a proper entity chain.
--- gcc/ada/exp_util.adb
+++ gcc/ada/exp_util.adb
@@ -1977,6 +1977,7 @@ package body Exp_Util is
       Set_Scope (Obj_Id, Proc_Id);
 
       Set_First_Entity (Proc_Id, Obj_Id);
+      Set_Last_Entity  (Proc_Id, Obj_Id);
 
       --  Generate:
       --    procedure <Work_Typ>DIC (_object : <Work_Typ>);