bitbake: event/runqueue: Drop StampUpdate event, its pointless/unused

Whilst this class has existed for years, it doesn't have any
users and has a questionable interface. Drop it to allow for further
simplification and changes.

(Bitbake rev: 3ab51764f7965d696bb2c5a872bf161473df4289)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/ui/knotty.py

@@ -660,7 +660,6 @@ def main(server, eventHandler, params, tf = TerminalFilter):
             # ignore
             if isinstance(event, (bb.event.BuildBase,
                                   bb.event.MetadataEvent,
-                                  bb.event.StampUpdate,
                                   bb.event.ConfigParsed,
                                   bb.event.MultiConfigParsed,
                                   bb.event.RecipeParsed,