osx: prefs pane should properly detect version

osx: prefs pane should properly detect version

we use "new" afs conf after 1.4.6 or 1.5.36. detect correctly

Reviewed-on: http://gerrit.openafs.org/4254
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit 0016e013aa012e179e7ac4c59b19a0ee1cbd0840)

Change-Id: I6796dee249eccd7646359deb8f29322b9954f803
Reviewed-on: http://gerrit.openafs.org/4269
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>