salvaged: Break volume callbacks on vol change

salvaged: Break volume callbacks on vol change

The salvager code can change a volume in many ways as it fixes errors.
We should break callbacks on the volume whenever we change it, as
clients may have callbacks on whatever we changed. So, for the
salvageserver, send an FSSYNC command to the fileserver to tell it to
break callbacks for that volume.

FIXES 127030

Change-Id: I1cd869371167df7d4e55ac14400865fb0a9c5154
Reviewed-on: http://gerrit.openafs.org/2210
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>