DAFS: Skip hosts with invalid flags on restore

DAFS: Skip hosts with invalid flags on restore

Host entries with HWHO_INPROGRESS set or ALTADDR unset do not have
valid state, since those flags indicate that the fileserver was in the
middle of identifying the host when the host struct was serialized.
Skip entries from the on-disk host data that have such invalid flags
set when restoring state, so we do not load invalid data.

Change-Id: I26b88256679f4596598e6e3e6b68af7e8e5e387d
Reviewed-on: http://gerrit.openafs.org/5527
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementix.org>