volser: 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)

Reviewed-on: http://gerrit.openafs.org/9352
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
(cherry picked from commit 4f9ec8396d1c7f12f8fa264cea7c255ce62b7b8d)

Change-Id: I7e2dfcaf23312dde123515e2c7329df1fa62de3e
Reviewed-on: http://gerrit.openafs.org/11038
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Chas Williams - CONTRACTOR <chas@cmf.nrl.navy.mil>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>