xfstests: test dump/restore of file capabilities

xfstests: test dump/restore of file capabilities

xfsrestore isn't properly restoring file capabilities; it restores
them, but then chowns the file, which removes the caps:

Call Trace:
 [<ffffffffa028de68>] xfs_xattr_set+0x118/0x120 [xfs]
 [<ffffffff8119a8c0>] generic_removexattr+0x80/0x90
 [<ffffffff8120b408>] cap_inode_killpriv+0x28/0x30
 [<ffffffff8120c666>] security_inode_killpriv+0x16/0x20
 [<ffffffff81192edf>] notify_change+0x18f/0x330
 [<ffffffff81176b70>] chown_common+0x60/0xa0
 [<ffffffff81176c30>] sys_fchown+0x80/0xd0
 [<ffffffff81537c59>] system_call_fastpath+0x16/0x1b

This test demonstrates the problem.

Reported-by: fugazzi® <fugazzi99@gmail.com>
Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Ben Myers <bpm@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>