EX-4965 lipe: use new e2fsprogs xattr API in lipe_scan3

EX-4965 lipe: use new e2fsprogs xattr API in lipe_scan3

In lipe_scan3, switch to the ext2fs_xattr_handle API since this
handles xattrs stored in a separate file. Update sanity-lipe-scan3
test_108() to verify.

Test-Parameters: trivial testlist=sanity-lipe-find3
Test-Parameters: trivial testlist=sanity-lipe-scan3
Signed-off-by: John L. Hammond <jhammond@whamcloud.com>
Change-Id: I307d78ba03c6612e5787f71a4682c0af5b23f1c5
Reviewed-on: https://review.whamcloud.com/46875
Tested-by: jenkins <devops@whamcloud.com>