in mk/bsd.pkg.mk:

##### Prevent /etc/mk.conf from being included by a distribution's BSD-style
##### Makefiles.  We really don't want to pick up settings that are used by
##### builds in /usr/src, e.g. DESTDIR.
MAKE_ENV+=      MAKECONF=/dev/null

this prevents my 1.4.3 a.out i386 from updating pkgtools, since without
OBJECT_FMT defined, bsd.own.mk defines OBJECT_FMT=ELF which puts in
dependencies for /usr/lib/crtbegin.o, which of course doesn't exist on
an a.out system.

if not /etc/mk.conf, where else am I supposed to set OBJECT_FMT and
CFLAGS and the like?

-- 
  Aaron J. Grier | "Not your ordinary poofy goof." | agrier@poofygoof.com