ext4: properly align shifted xattrs when expanding inodes

ext4: properly align shifted xattrs when expanding inodes

We did not count with the padding of xattr value when computing desired
shift of xattrs in the inode when expanding i_extra_isize. As a result
we could create unaligned start of inline xattrs. Account for alignment
properly.

CC: stable@vger.kernel.org  # 4.4.x-
Signed-off-by: Jan Kara <jack@suse.cz>
(cherry picked from commit 443a8c41cd49de66a3fda45b32b9860ea0292b84)

Orabug: 25718971

Signed-off-by: Shuning Zhang <sunny.s.zhang@oracle.com>
Reviewed-by: Junxiao Bi <junxiao.bi@oracle.com>
Signed-off-by: Brian Maly <brian.maly@oracle.com>