plain 0 should be used. This happens to work because we #define NULL to 0, but is stylistically wrong and can cause problems for people trying to port bits of code to other environments. PR: 2752 Submitted by: Arne Henrik Juul <arnej@imf.unit.no>
OpenBSD has a similar code, but this was indepenent.
Closes FreeBSD PR#2685. Obtained from: NetBSD-BUGS PR# 3199