ubik: Abstract common code in ContactQuorum* functions

ubik: Abstract common code in ContactQuorum* functions

These functions are mostly identical except for the arguments and the
called operation.  Move as much common code as possible to an iterator
function and a return code check function.  The DISK_WriteV case is
treated a bit differently since it can fall back to using DISK_Write.

This reduces code duplication and shoud simplify maintenance and
future changes.  There should be no functional changes.

Change-Id: If2f88c670da47eaad4baa81975ecc307013f5ce8
Reviewed-on: http://gerrit.openafs.org/3970
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Andrew Deason <adeason@sinenomine.net>
Reviewed-by: Jeffrey Altman <jaltman@openafs.org>
Reviewed-by: Derrick Brashear <shadow@dementia.org>