audit: remove uneeded strncpy

audit: remove uneeded strncpy

In this caller to krb_realms, when no realms names are returned the
number of local realms is correctly set to zero, however the first
local realm buffer is filled with a placeholder string which is
not used.  Remove the uneeded strncpy, which also makes this
section of code consistent with afs_is_foreign_ticket().

This section of code is duplicated by afs_is_foreign_ticket() and
should be consolidated in a subsequent patch.

Change-Id: I48f84934e7321769eebaf80c83b2c100fd026a6a
Reviewed-on: http://gerrit.openafs.org/5020
Reviewed-by: Simon Wilkinson <sxw@inf.ed.ac.uk>
Tested-by: Simon Wilkinson <sxw@inf.ed.ac.uk>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>