bitbake/event.py: UIhandler filter should work without a mask

The default for the mask will be * (all the handlers)

Signed-off-by: Cristiana Voicu <cristiana.voicu@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
hob: add event handlers filtering in Hob

Create the _evt_list for hob; it is longer than the knotty
uses because it handles more events.

Signed-off-by: Cristiana Voicu <cristiana.voicu@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>