qcow2: Repair OFLAG_COPIED when fixing leaks

qcow2: Repair OFLAG_COPIED when fixing leaks

Repairing OFLAG_COPIED is usually safe because it is done after the
refcounts have been repaired.  Therefore, it we did not find anyone else
referencing a data or L2 cluster, it makes no sense to not set
OFLAG_COPIED -- and the other direction (clearing OFLAG_COPIED) is
always safe, anyway, it may just induce leaks.

Furthermore, if OFLAG_COPIED is actually consistent with a wrong (leaky)
refcount, we will decrement the refcount with -r leaks, but OFLAG_COPIED
will then be wrong.  qemu-img check should not produce images that are
more corrupted afterwards then they were before.

Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1527085
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 20180509200059.31125-2-mreitz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>