Chroot first appeared in 4.3-Reno, not in 4.4 in the BSD world,
but in System III in the AT&T world.

Examination of the TUHS archives shows this was present in 4.3-Reno
and System III.

Reviewed by: 0mp@, allanjude@
MFC After: 3 days
Differential Revision: https://reviews.freebsd.org/D25479