ptserver: Incorrect variable used to print error msg

ptserver: Incorrect variable used to print error msg

In testpt.c the variable cdir is used to print the name of the temporary
dir.  However at this point in the code cdir is NULL and the variable
tmp_conf_dir contains the actual name that should be used in the error
message.

Flagged as an error when --enable-checking is on and using GCC 9.

Reviewed-on: https://gerrit.openafs.org/13662
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
(cherry picked from commit f938f5f248a3cb3f7ac871f5ef45a0e2d043706b)

Change-Id: I1b993ddc2545f90736811e2eb85ba4b3bae6e657
Reviewed-on: https://gerrit.openafs.org/13728
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>