xfs/010: explicitly allow corrupted write in xfs_db

xfs/010: explicitly allow corrupted write in xfs_db

xfs/010 wants to write corruption and test how xfs_repair
deals, but when:

  xfs: forbid AG btrees with level == 0

is merged to userspace, this new test fails the write verifier
in xfs_db.

Add "-c" to allow the corrupted write, do the corruptions all
in one xfs_db command (so it doesn't have to re-read the
corrupted data on 2nd startup), and filter out the

  "Allowing write of corrupted data and bad CRC"

output from the "write -c" command.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>