Add -lxo (for df) and -lgpio(for gpioctl) to bsdbox.  This will allow the picostation
build to work again.

Reviewed by:	adrian


git-svn-id: svn+ssh://svn.freebsd.org/base/head@275621 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f