Fix setting wxPG_ARRAY_DELIMITER attribute

This attribute is used only to set internal data member in wxArrayStringProperty and thus can be considered as a built-in attribute which doesn't have to be stored in the property's attribute store.

src/propgrid/props.cpp

@@ -2923,9 +2923,9 @@ bool wxArrayStringProperty::DoSetAttribute( const wxString& name, wxVariant& val
     {
         m_delimiter = value.GetChar();
         GenerateValueAsString();
-        return false;
+        return true;
     }
-    return true;
+    return false;
 }
 
 // -----------------------------------------------------------------------