Following the recent discussion about rebuilding the system, I
added the following lines to /etc/mk.conf:

#ifndef BSD_PKG_MK
MAKEOBJDIR=/usr/obj
DESTDIR=/usr/netbsd
#endif

and ran

PATH=$PATH:/usr/tools/bin ./build.sh -T /usr/tools distribution kernel=CHALLENGER

It all worked, with one notable exception:  the .o files are all in /usr/src,
rather than /usr/obj.  I thought that setting MAKEOBJDIR would take
care of that.  (The build did indeed go to /usr/netbsd.)  What am I doing
wrong?