NetBSD: DEBUG can not typically be defined

NetBSD: DEBUG can not typically be defined

Like IRIX 6.5, some NetBSD kernel structures change size in the presence
of the DEBUG preprocessor symbol.

Reviewed-on: http://gerrit.openafs.org/4605
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit 48633351c597278d4c8efd5a80163f0637c85aaf)

Change-Id: I15771316dc657474d8b906df26f927fdbefe384c
Reviewed-on: http://gerrit.openafs.org/4617
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>