Print "waiting for job termination" at most once.

This message is useless, annoying, and is the UI equivalent of littering... but
it does explain why your backup command is just sitting there.

Reviewed-on: http://gerrit.openafs.org/6223
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@secure-endpoints.com>
(cherry picked from commit 6d6d52e18f3bd537331de6021a0fcc2e96fc48db)

Change-Id: Ide51c7ef7c40426f34a5f1cb6c23395b0d93886a
Reviewed-on: http://gerrit.openafs.org/9438
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Tested-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>