cryptfs: kill processes with open files on tmpfs /data

cryptfs: kill processes with open files on tmpfs /data

cryptfs will fail to remount /data at boot if any processes (e.g.
dex2oat) have files open on the tmpfs /data partition.  Since these
files are about to be destroyed anyway, just kill the offending
processes: first with SIGHUP and finally with SIGKILL.

Also remove a stray i++ that effectively cut the number of retries in
half.

Bug: 17576594

Change-Id: I76fb90ce2e52846ffb9de706e52b7bde98b4186a
Signed-off-by: Greg Hackmann <ghackmann@google.com>