(This is part of a larger changeset which is intended to reduce diff only,
thus some prototypes were left intact since they will be changed in the
future).
Verified with: md5(1)
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>