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

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.

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

gcc/ada/

	* lib-xref-spark_specific.adb (Create_Heap): Set dummy Etype for
	the fake __HEAP entity.

From-SVN: r273216

gcc/ada/ChangeLog

+2019-07-08  Piotr Trojanek  <trojanek@adacore.com>
+
+	* lib-xref-spark_specific.adb (Create_Heap): Set dummy Etype for
+	the fake __HEAP entity.
+
 2019-07-08  Daniel Mercier  <mercier@adacore.com>
 
 	* gnat1drv.adb: Suppress warnings on memory representation in

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;