ext4: let empty_dir handle inline dir

empty_dir is used when deleting a dir.  So it should handle inline dir
properly.

Signed-off-by: Tao Ma <boyu.mt@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --cc fs/ext4/inline.c
Simple merge

diff --cc fs/ext4/namei.c
Simple merge

diff --cc fs/ext4/xattr.h
Simple merge