multipath: add queue_without_daemon config parameter

multipath: add queue_without_daemon config parameter

This patch adds a new multipath.conf default paramter, queue_without_daemon.
If this is set to "no", when multipathd stops, queueing will be turned off for
all devices.  This is useful for devices that set no_path_retry.  If a machine
is shut down while all paths to a device are down, it is possible to hang
waiting for IO to return from the device after multipathd has been stopped.
Without multipathd running, access to the paths cannot be restored, and the
kernel cannot be told to stop queueing IO. Setting queue_without_daemon to "no"
makes multipathd turn off queueing on all devices when it stops, avoiding the
problem.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>