[Ada] Set dummy Etype for the fake __HEAP entity in GNATprove

[Pierre-Marie de Rodat]

GNATprove represents reads and writes via pointers as operations on a
fake __HEAP entity. This entity already had various properties set to
dummy values (e.g. Scope set to Standard_Standard), so that it can be
processed like other entities without crashing and not special-cased
everywhere. Now it also has a dummy Etype, so it can be processed with
Is_Single_Concurrent_Object.

The modified code is only executed by GNATprove; frontend is not
affected.

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

2019-07-08  Piotr Trojanek  <troja...@adacore.com>

gcc/ada/

        * lib-xref-spark_specific.adb (Create_Heap): Set dummy Etype for
        the fake __HEAP entity.
--- gcc/ada/lib-xref-spark_specific.adb
+++ gcc/ada/lib-xref-spark_specific.adb
@@ -298,6 +298,7 @@ package body SPARK_Specific is
 
          Set_Ekind       (Heap, E_Variable);
          Set_Is_Internal (Heap, True);
+         Set_Etype       (Heap, Standard_Void_Type);
          Set_Scope       (Heap, Standard_Standard);
          Set_Has_Fully_Qualified_Name (Heap);
       end Create_Heap;