Make OpenAFS 1.6.8pre1

prerelease for 1.6.8

Change-Id: I1b0632aa5b76ecff1690fb252eb3427aa17aaad0
Reviewed-on: http://gerrit.openafs.org/10893
Reviewed-by: D Brashear <shadow@your-file-system.com>
Reviewed-by: Jeffrey Altman <jaltman@your-file-system.com>
Tested-by: Chas Williams - CONTRACTOR <chas@cmf.nrl.navy.mil>
Reviewed-by: Chas Williams - CONTRACTOR <chas@cmf.nrl.navy.mil>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>