xfs_db: Allow writes of corrupted data

xfs_db: Allow writes of corrupted data

Being able to write corrupt data is handy if we wish to test
repair against specific types of corruptions.

Add a "-c" option to the write command which allows this by removing
the write verifier.

Note that this also skips CRC updates; it's not currently possible
to write invalid data with a valid CRC; CRC recalculation is
intertwined with validation.

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>