Handler definition for the automatic dispatch implementation for the particular I/O mechanism selected.
This handler is used by:
If this handler is implemented, the VortexIoHaveDispatch must also be implemented, making it to always return axl_true. If this two handler are implemented, its is not required to implement the "is set?" functionality provided by VortexIoIsSetFdGroup (vortex_io_waiting_set_is_set_fd_group).