Updates from NetBSD (cgd):
- seriously clean up makefiles. use libsa/libkern/libz as appropriate,
and don't build the various sources into objs locally by specifying
them directly in the Makefiles.
- move the secondary bootstrap down (to 0x20004000), and add a HEAP_LIMIT
so that we don't exhaust our bootstrap address space (when using the new,
not yet checked in, memory allocator).
- clean up installboot, deal with secondary bootstrap programs not on
'a' partition or 'a' partition not starting at 0.
- add padding to structures in bbinfo.h for future expansion. Add a
netbbinfo structure to allow netboot information to be hard-coded in
network boot blocks, so that they can be made to work even on systems
with firmware which doesn't support the new "ethernet address in boot
device" convention.
- move the sync() calls to the correct place in installboot.c
- remove a kludge in disk.c which was breaking multiple opens/closes
of the disk
- allow netboot ethernet address to be hard-coded into binary so that
machines with old firmware which doesn't pass it in the boot device
can work. Assume that if the ethernet address isn't passed in, it
uses the old (dain-bramaged) 'read' interface works on my 3000/300LX.
- Add setnetbootinfo, a program to hard code an ethernet address into
a network boot.
- move an 'int debug;' into boot.c (it was the only diff between boot.c and
netboot.c), and nuke netboot.c (using boot.c instead for net boot blocks).
- add cd9660 file system ops to the file system ops table in filesystem.c
- if a file name is given (i.e. BOOTED_FILE) is set, boot only that file,
but if not then try to boot "bsd", "bsd.bak", "bsd.old", and
"obsd" (in that order) until one is found or until the list of names
is exhausted.
- add support for reading gzipped kernels.
- use strerror() to print errors, rather than just printing error numbers
- if no disk label exists, fake one up
- slightly relax the block size checks in bootxx.c; they were a bit to paranoid

And local changes:
- don't build a copy of libsa/libkern/libz for each boot prog,
just build a single copy and use it for everything.