macos: update decode-panic

fix a couple brain-os from the last round of updates, so it can
actually decode panics.

Change-Id: If39f1fb273a834d0618264d944387bd8b6751284
Reviewed-on: http://gerrit.openafs.org/8929
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Tested-by: Derrick Brashear <shadow@your-file-system.com>