Import of code from heimdal

Import of code from heimdal

This commit updates the code imported from heimdal to
4a438db29d361b7e5f47b86ced1482a96cde86ea (switch-from-svn-to-git-3008-g4a438db)

Upstream changes are:

Michael Meffie (1):
      drop __restrict some more, to please old compilers

Change-Id: Ibe62c9abd661793d11f379c13cc3b93f198a1e8d
Reviewed-on: http://gerrit.openafs.org/8003
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>