OpenBSD (and likely NetBSD, but it's not enabled for these tests
anyway) use a different sysctl API for fetching process information
than FreeBSD and its derivatives.

Change-Id: Id2ab10f170b788ba4d9bd45d3347f530555da23b
Reviewed-on: https://go-review.googlesource.com/19232Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>