metadump: include NULLFSINO check in inode copy code

metadump: include NULLFSINO check in inode copy code

The copy_ino() function includes a check for effectively NULL inode
numbers. It checks for 0 but does not include NULLFSINO. This leads to
spurious warnings in some instances. For example, copy_ino() is called
unconditionally for sb quota inodes from copy_sb_inodes(), values of
which can be NULLFSINO.

Check for NULLFSINO and return quietly from copy_ino().

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