viced: Allow checkout of VOL_STATE_DELETED volumes

viced: Allow checkout of VOL_STATE_DELETED volumes

The fileserver allows nonexistent volumes to be checked out. Since
VOL_STATE_DELETED volumes conceptually do not exist, we should also
allow them to be checked out.

Reviewed-on: http://gerrit.openafs.org/2873
Reviewed-by: Tom Keiser <tkeiser@sinenomine.net>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit 88fc9ada4cfaee354199480916d139400ee0ef5b)

Change-Id: I24bf2100bf57a27323cd0e9e5081e767e67c944e
Reviewed-on: http://gerrit.openafs.org/4261
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit ee2811b01f3c34d3f07802ff88e2577da1caef6d)