This change is a followup to https://go-review.googlesource.com/23967
for FreeBSD.

Updates #13987.
Updates #16028.

Change-Id: I0f0737372fce6df89d090fe9847305749b79eb4c
Reviewed-on: https://go-review.googlesource.com/24021Reviewed-by: Ian Lance Taylor <iant@golang.org>