redhat: Don't replace modified configuration files during rpm update

redhat: Don't replace modified configuration files during rpm update

The previous setting for three %config files mentioned in the spec file:

%config /etc/sysconfig/openafs
%config %{_prefix}/vice/etc/ThisCell
%config %{_prefix}/vice/etc/cacheinfo

When using an unadorned %config, it's possible that these files will
be replaced by the packaged version during a package update.  Changing
%config to %config(noreplace) means that the packaged file will be
installed with the extension .rpmnew if there is already a modified
(from the existing package's version) file with the same name on the
installed machine.

The concern here is that updating an existing system could potentially
change the configuration if the person installing doesn't pay close
attention.  The Rule of Least Surprise indicates that we should
try to preserve existing configuration changes whenever possible.

Change-Id: Ie132c12a3c5defe9bf6fec9ec0f8bd08f3d98646
Reviewed-on: http://gerrit.openafs.org/6887
Reviewed-by: Derrick Brashear <shadow@dementix.org>
Tested-by: Derrick Brashear <shadow@dementix.org>
Reviewed-on: http://gerrit.openafs.org/6889
Tested-by: BuildBot <buildbot@rampaginggeek.com>