I just tried to build an LKM on a system with no kernel source
installed and independently discovered the bug first reported by
Stefan Grefen in PR 5377 in April.

That PR led to a lively philosophical discussion on netbsd-bugs about
system headers in general and the need to include <sys/systm.h> from
userland in particular.  Interesting as it was, to me that discussion
seems irrelevant with respect to the actual bug: the bug specifically
affects LKMs, and non-one has questioned the need to to include
<sys/systm.h> from an LKM, whether built inside the kernel source tree
or not.

So, could someone please just integrate the fix?
-- 
Andreas Gustafsson, gson@araneus.fi