Update libxo to 0.6.3

[ngie]

Summary

Update libxo to 0.6.3

This fixes the 02 testcases on i386 (at least), but may fix it in general on
32-bit platforms

Sponsored by: EMC / Isilon Storage Division

Test Plan

Run kyua test on amd64/i386, e.g.

$ (cd lib/libxo/tests; make check)
...
functional_test:test_11X -> passed [0.032s]
functional_test:test_11XP -> passed [0.035s]

Results file id is usr_tests_lib_libxo.20160702-053539-944925
Results saved to /home/ngie/.kyua/store/results.usr_tests_lib_libxo.20160702-053539-944925.db

99/99 passed (0 failed)
$ uname -a
FreeBSD fbsd11-i386.local 11.0-ALPHA5 FreeBSD 11.0-ALPHA5 #1 r301745+978d049(master): Thu Jun 30 18:03:32 PDT 2016 [e-mail]:/usr/obj/usr/src/git/sys/GENERIC i386
$

[phil]

Thanks!!

[ngie]

rS302321