macos: upgrade *.xib files

macos: upgrade *.xib files

According to Xcode 11, the *.xib files updated by this commit use an
older format that is potentially insecure when decoded. To fix this
problem, Xcode automatically upgraded these files to the modern format.
These changes are required to build OpenAFS on Catalina (Xcode 11).

Reviewed-on: https://gerrit.openafs.org/13935
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
(cherry picked from commit d4302d42149988fa6d04d626967063dfa916c9fd)

Change-Id: I1e29493a8431d4ad13ff36762f6112dd5309573c
Reviewed-on: https://gerrit.openafs.org/14032
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Cheyenne Wills <cwills@sinenomine.net>
Reviewed-by: Michael Meffie <mmeffie@sinenomine.net>
Reviewed-by: Mark Vitale <mvitale@sinenomine.net>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>