shutdown. (Portmap and statd are needed during shutdown to unmount
NFS volumes but have open files in /var/run.)
* In the shutdown job, don't kill PIDs belonging to Upstart jobs that
are still running. If they don't stop on the "starting shutdown"
event, then they're needed during shutdown (such as portmap and
statd).
* NFS test: test whether the shutdown quickly unmounts NFS volumes
(i.e. whether portmap and statd are still running).
svn path=/nixos/branches/boot-order/; revision=22204
