[Ada] Add adequate guard before calling First_Rep_Item

gcc/ada/

	* sem_ch13.adb (Build_Predicate_Functions): Add guard.
diff --git a/gcc/ada/sem_ch13.adb b/gcc/ada/sem_ch13.adb
index 8bc8490..595a741 100644
--- a/gcc/ada/sem_ch13.adb
+++ b/gcc/ada/sem_ch13.adb
@@ -10104,7 +10104,10 @@
          --  If the type is private, check whether full view has inherited
          --  predicates.
 
-         if Is_Private_Type (Typ) and then No (Ritem) then
+         if Is_Private_Type (Typ)
+           and then No (Ritem)
+           and then Present (Full_View (Typ))
+         then
             Ritem := First_Rep_Item (Full_View (Typ));
          end if;