jobd.pl: include duration in "Queue processed" line
Instead of just showing "Queue processed.", add a human-readable
duration. For example, "Queue processed in 15s.".
Although the duration can be computed from the time stamps, it's
not readily apparent what the magnitude of the difference in
processing times between queue runs might be.
By adding an explicit human-readable duration, orders of magnitude
differences in queue processing times will become readily apparent.
Signed-off-by: Kyle J. McKay <mackyle@gmail.com>