Fix build on recent NetBSD 6.99.16.
See http://cvsweb.netbsd.org/bsdweb.cgi/src/sys/sys/sysctl.h.diff?r1=1.204&r2=1.205&f=h&only_with_tag=MAIN&f=u

Tested on NetBSD/i386 5.2 and NetBSD/amd64 current.

Patch is provided from nonaka@. Thank you.
Bump PKGREVISION for previous commit.