defined parameters to avoid unmet dependency

These parameters are set by the extension; but
validator.mapping.loader.annotation_loader.namespaces is not set when
annotations are disabled

src/Symfony/Bundle/FrameworkBundle/Resources/config/validator.xml

@@ -15,6 +15,9 @@
         <parameter key="validator.mapping.loader.xml_files_loader.class">Symfony\Component\Validator\Mapping\Loader\XmlFilesLoader</parameter>
         <parameter key="validator.mapping.loader.yaml_files_loader.class">Symfony\Component\Validator\Mapping\Loader\YamlFilesLoader</parameter>
         <parameter key="validator.validator_factory.class">Symfony\Bundle\FrameworkBundle\Validator\ConstraintValidatorFactory</parameter>
+        <parameter key="validator.mapping.loader.annotation_loader.namespaces" type="collection" />
+        <parameter key="validator.mapping.loader.xml_files_loader.mapping_files" type="collection" />
+        <parameter key="validator.mapping.loader.yaml_files_loader.mapping_files" type="collection" />
     </parameters>
 
     <services>