Fix ktime test for errors

Fix ktime test for errors

The variable passed into ktime_DateToLong must be initialized to 0
or, on error, we get the previous value and the tests fail.

Change-Id: I5528a830981a85fb6737bb8cb5931ab95faffb13
Reviewed-on: http://gerrit.openafs.org/2379
Tested-by: Russ Allbery <rra@stanford.edu>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit 9e2aba99124f777a209d30ea57cbe92e19130b1f)