[Ada] Fix ignored dynamic predicates specified through "predicate" aspect

[Pierre-Marie de Rodat]

Before this patch, GNAT would ignore dynamic predicates specified
through the "predicate" pragma when attempting to evaluate expressions.
This would result in incorrect behavior in cases like the following:

   subtype SS is String (1 .. 4) with Predicate => SS (2) = 'e';
   pragma Assert ("aaaa" in SS);

Where the assert would not fail.

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

gcc/ada/

        * sem_eval.adb (Is_Static_Subtype): Take predicates created
        through "predicate" pragma into account.
diff --git a/gcc/ada/sem_eval.adb b/gcc/ada/sem_eval.adb
--- a/gcc/ada/sem_eval.adb
+++ b/gcc/ada/sem_eval.adb
@@ -5741,6 +5741,8 @@ package body Sem_Eval is
       elsif Has_Dynamic_Predicate_Aspect (Typ)
         or else (Is_Derived_Type (Typ)
                   and then Has_Aspect (Typ, Aspect_Dynamic_Predicate))
+        or else (Has_Aspect (Typ, Aspect_Predicate)
+                  and then not Has_Static_Predicate (Typ))
       then
          return False;