chattr/lsattr: Support dax attribute

Use the letter 'x' to set/get dax attribute on a directory/file.

Signed-off-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
4 files changed