xfs_io: implement 'inode' command

xfs_io: implement 'inode' command

Implements a new xfs_io command, named 'inode', which is supposed to be
used to query information about inode's existence and its physical size
in the filesystem.

Supported options:

Default:     -- Return true(1) or false(0) if any inode greater than
                32bits has been found in the filesystem
[num]        -- Return inode number or 0 if the inode [num] is in use
-n [num]     -- Return the next valid inode after [num]
-v           -- verbose mode
                Display the inode number and its physical size according to the
		argument used

Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Bill O'Donnell <billodo@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>