Use lsof to check for processes that still open /dev/mcosX at shutdown
time.
If lsof is not installed then the check is just not done (empty PROCS
result)
If -k is not passed, print a message listing pids of users and exit
(taking bets someone will use that and sed to kill out of mcstop+release
and rerun the stop script instead of passing -k at some point)
Change-Id: Idba7486fdede4990d9885d23f8077f33839daeed
c96dfb0c68