Here's what I get...
/usr/src/sys/lib# make
===> libsa
===> libc_sa
===> libkern
-O -I/arch/m68k    -c adddi3.c
-O: not found
*** Error code 1

Stop.
*** Error code 1

Stop.

... So far as I can tell, KERNCC is not getting set anywhere, but
the libkern makefile assumes that it is set.  This is with M68K - anyone
else see this?  Which of the fourteen Foolish Mistakes have I made this
time?

-s