XXX: Make we somehow more descriptive

Building a FreeBSD kernel i386 called DEBUG on an amd64 can cause some headache:
build# sh -c 'MACHINE_ARCH=i386 MACHINE=i386 MAKEOBJDIRPREFIX=/usr/obj/nanobsd.wleiden/i386 make KERNCONF=DEBUG NO_MODULES=yes buildkernel'

Then install kernel CF is mounted at /mnt :
# sh -c 'MACHINE_ARCH=i386 MACHINE=i386 MAKEOBJDIRPREFIX=/usr/obj/nanobsd.wleiden/i386 make KERNCONF=DEBUG NO_MODULES=yes installkernel PREFIX=/mnt'