Add libxo(3) to mount(8) and acpiconf(8)

From: Cameron Katri via freebsd-current <freebsd-current_at_freebsd.org>
Date: Wed, 19 May 2021 20:35:27 UTC
I just submitted two differentials to add libxo(3) support to mount(8) 
and acpiconf(8).

https://reviews.freebsd.org/D30341
https://reviews.freebsd.org/D30350

- Cameron Katri