make openafs 1.6.2pre4

prerelease for 1.6.2

Change-Id: I012e498c5a2a46c0f712f453de03c98b0a5a5187
Reviewed-on: http://gerrit.openafs.org/8989
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Paul Smeddle <paul.smeddle@gmail.com>