libext2fs: handle inline data in dir iterator function

libext2fs: handle inline data in dir iterator function

Inline_data is handled in dir iterator because a lot of commands use
this function to traverse directory entries in debugfs.  We need to
handle inline_data individually because inline_data is saved in two
places.  One is in i_block, and another is in ibody extended attribute.

After applied this commit, the following commands in debugfs can
support the inline_data feature:
	- cd
	- chroot
	- link*
	- ls
	- ncheck
	- pwd
	- unlink

* TODO: Inline_data doesn't expand to ibody extended attribute because
  link command doesn't handle DIR_NO_SPACE error until now.  But if we
  have already expanded inline data to ibody ea area, link command can
  occupy this space.

Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>