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

Updates #13987.
Updates #16028.

Change-Id: Ib1fb9f957fafd0f91da6fceea56620e29ad82b00
Reviewed-on: https://go-review.googlesource.com/24020Reviewed-by: Ian Lance Taylor <iant@golang.org>