ubik: death to orphaned signals

ubik: death to orphaned signals

ubik has a few very old "orphaned" LWP events that are signalled via
LWP_NoYieldSignal, but have no matching waits (LWP_WaitProcess).

Each "signal" runs the LWP waiting element list for each LWP on the
blocked queue; this may add up to substantial wasted overhead on a
heavily loaded ubik server.

Remove the orphaned signals.

No functional difference should be incurred by this commit.

Change-Id: I66eba45975a829216e7af1927e51ec6aab63f570
Reviewed-on: https://gerrit.openafs.org/12620
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Marcio Brito Barbosa <mbarbosa@sinenomine.net>
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
Tested-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>