LU-10030 llite: extend inode flags into GET/SETXATTR ioctl

LU-10030 llite: extend inode flags into GET/SETXATTR ioctl

This is very useful for projet quota tools to save RPC call
to change project inherit attribute together with project ID.

Change-Id: I5b545bf2c5c601b552a85322c80994dabbca0b12
Signed-off-by: Wang Shilong <wshilong@ddn.com>
Reviewed-on: https://review.whamcloud.com/30072
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Yingjin Qian <qian@ddn.com>