Convert ls(1) to not use libxo(3).

[cem]

Summary

libxo imposes a large burden on system utilities. In the case of ls, that
burden is difficult to justify -- any language that can interact with json
output can use readdir(3) and stat(2).

Logically revert r291607, r285857, r285803, r285734, r285425, r284494, r284489,
r284252, and r284198.

Test Plan

$ id
uid=0(root) gid=0(wheel) groups=0(wheel),5(operator)
$ kyua test
...
35/35 passed (0 failed)

[imp]

My only regret is that phab won't let me click accept twice.