debugfs: output large directory size

debugfs: output large directory size

large_dir option allows to create directory with size > 2GB.
debugfs utility outputs negative size value for large directories
and ignores high part of directory size.

Fix debugfs to use high part of directory size in debugfs output
and use appropriate output format.

Signed-off-by: Artem Blagodarenko <artem.blagodarenko@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>