Linux: deal with ctl_name removal

Linux: deal with ctl_name removal

The binary sysctl interface will be removed in kernel 2.6.33 and
ctl_name will be dropped from the ctl_table structure.
Make the code that uses ctl_name conditional on a configure test.

(cherry picked from commit 886801b069fab1e6fc94003221dcfe18e05ac376)

Change-Id: Iba0f107f299c6515e4e560d7596e6187bd68e399
Reviewed-on: http://gerrit.openafs.org/904
Tested-by: Marc Dionne <marc.c.dionne@gmail.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Reviewed-on: http://gerrit.openafs.org/1013
Tested-by: Derrick Brashear <shadow@dementia.org>