salvager: Clear summary in RecordHeader

salvager: Clear summary in RecordHeader

Not every field in the summary header in RecordHeader is set, leaving
some used uninitialized when we copy to the given volumeSummaryp (like
'deleted'). Zero out the header before we do anything.

Reviewed-on: http://gerrit.openafs.org/4876
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
(cherry picked from commit 926ce3d35018050bdbe8e00011884954d6b0fd80)

Change-Id: Ia617153da8762394659b7c7816e6f3d24af6c4d2
Reviewed-on: http://gerrit.openafs.org/4944
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>