libadmin: Don't overflow volume name

libadmin: Don't overflow volume name

The maximum volume name length in the VLDB RPCs is VL_MAXNAMELEN
(65), not 64 as used as a hardcoded value in vsprocs. Switch to
using the defined value, and also use strlcat to check that we
don't overflow this.

Caught by coverity (#985849)

Change-Id: Idde2cf8362bbd48538fafcd8c8d98e1f71cc15e1
Reviewed-on: http://gerrit.openafs.org/9353
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>