cd ${KERNSRCDIR}/${KERNARCHDIR}/compile && ${PRINTOBJDIR}
This is far simpler than the previous system, and more robust with
objdirs built via BSDOBJDIR.
The previous method of finding KERNOBJDIR when using BSDOBJDIR by
referencing _SRC_TOP_OBJ_ from another directory was extremely
fragile due to the depth first tree walk by <bsd.subdir.mk>, and
the caching of _SRC_TOP_OBJ_ (with MAKEOVERRIDES) which would be
empty on the *first* pass to create fresh objdirs.
This change requires adding sys/arch/*/compile/Makefile to create
the objdir in that directory, and descending into arch/*/compile
from arch/*/Makefile. Remove the now-unnecessary .keep_me files
whilst here.
Per lengthy discussion with Andrew Brown.
Defaults to the directory determined by the _SRC_TOP_ logic (if != ""),
and the BSDSRCDIR.
NETBSDSRCDIR has been provided for use by the various NetBSD source
Makefiles to find the top of the NetBSD source tree, and isn't
affected by the inheritance properties of _SRC_TOP_, nor does it
have the magic BSDOBJDIR baggage that BSDSRCDIR is stuck with.
Use the old setup for MAKEOBJDIRPREFIX but also add a new check for
_SRC_TOP_OBJ_ and use that if it's set. This allows a make release using
build.sh (which uses MAKEOBJDIR patterns) to function correctly on r/o
source tree's.
