declare(); is ignored, and contained "constant" is NOT declared

fixes incorrectly defining "strict_types" constant

src/Peachpie.CodeAnalysis/Semantics/Graph/BuilderVisitor.cs

@@ -509,9 +509,7 @@ public override void VisitBlockStmt(BlockStmt x)
 
         public override void VisitDeclareStmt(DeclareStmt x)
         {
-            Add(x);
-
-            base.VisitDeclareStmt(x); // visit inner statement, if present
+            // ignore declare();
         }
 
         public override void VisitGlobalCode(GlobalCode x)