OpenAFS Preference Pane 64bit and Symbolic Link features implemented.

OpenAFS Preference Pane 64bit and Symbolic Link features implemented.

Now the OpenAFS preference pane is compiled with 32 and 64 bit snowleopard support, so the preference
windows is no more restarted in 32 bit mode.
The tab for symbolic link creation has been implemented. Now the user can create and delete link.
For create a link both name and destination path must be set. AFSBackgrounder has been updated to
manager in a separate thread the link creation and destroy operation, according to the vaule of
checkbox "Enable Symbolic Link" in "Mounts" tab.

Reviewed-on: http://gerrit.openafs.org/677
Tested-by: Derrick Brashear <shadow@dementia.org>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit e82f3b210e0e49fb9d9531565f634ed9d49426a5)
Change-Id: Id974a25df6104de38ff4e9925c1a57b5e0f25112
Reviewed-on: http://gerrit.openafs.org/970