Fix potential fallthrough

taglib/asf/asfattribute.cpp

@@ -250,6 +250,7 @@ int ASF::Attribute::dataSize() const
   case BytesType:
     if(d->pictureValue.isValid())
       return d->pictureValue.dataSize();
+    break;
   case GuidType:
     return d->byteVectorValue.size();
   }