MacOS: don't install growlagent into prefpanes dir

MacOS: don't install growlagent into prefpanes dir

we have more than one tool now. don't misinstall into the
prefpanes directory

Reviewed-on: http://gerrit.openafs.org/3963
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit df7cca0fa8c5cbeca8cdb9f065e47f4c927dbbe3)

Change-Id: I9046dd9dbd0536a65b694a9331a86651bd1eeabd
Reviewed-on: http://gerrit.openafs.org/4088
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>