vlserver: use large enough buffer for rxinfo string

vlserver: use large enough buffer for rxinfo string

The "[dotted-quad] rxkad:name.inst@cell" construct can be as large as
(3*4+3)+7+3*64+2+1 == 217 characters (including trailing NUL); size
our buffer accordingly to avoid the risk of truncation.

Reviewed-on: https://gerrit.openafs.org/13466
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Cheyenne Wills <cwills@sinenomine.net>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
(cherry picked from commit 584b0f2b6b4391c0c879352bb1786c0f267666c9)

Change-Id: Ia11e685ec17f34a9a8fdc42d392b8a2677f63696
Reviewed-on: https://gerrit.openafs.org/13735
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Marcio Brito Barbosa <mbarbosa@sinenomine.net>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>