[Ada] Support access types in GNATprove

SPARK RM has been updated to support access types in SPARK. Part of this
support is that now SPARK RM 3.1 lists access types as having full
default initialization. Now updated.

There is no impact on compilation.

2018-12-11  Yannick Moy  <moy@adacore.com>

gcc/ada/

	* sem_util.adb (Has_Full_Default_Initialization): Consider
	access types as having full default initialization.

From-SVN: r266990

gcc/ada/ChangeLog

 2018-12-11  Yannick Moy  <moy@adacore.com>
 
+	* sem_util.adb (Has_Full_Default_Initialization): Consider
+	access types as having full default initialization.
+
+2018-12-11  Yannick Moy  <moy@adacore.com>
+
 	* gnat1drv.adb (Gnat1drv): Issue specific error message in
 	GNATprove mode when multiple file names on the command line.
 	* osint.adb, osint.ads (Dump_Command_Line_Source_File_Names):

gcc/ada/sem_util.adb

@@ -10880,6 +10880,11 @@ package body Sem_Util is
       if Is_Scalar_Type (Typ) then
          return Has_Default_Aspect (Typ);
 
+      --  An access type is fully default initialized by default
+
+      elsif Is_Access_Type (Typ) then
+         return True;
+
       --  An array type is fully default initialized if its element type is
       --  scalar and the array type carries aspect Default_Component_Value or
       --  the element type is fully default initialized.