Changes provoked by debugging / making 'PM: INIT died' error debuggable.
This was caused (in one instance) by a missing /dev/console (and everything
else) on the boot time ramdisk.
. sanity-check against this case by checking for console
. PM: print init stacktrace and exit status when init dies
. eliminate some explicitly invoked ${MAKE}s and a rm -rf in
Makefiles, causing race conditions; use explicit ordering (.WAIT)
instead, moving some of the burden of dependencies of partial builds
to the user. On the plus side, generate ramdisk just once.
. make mkfs.mfs fail as soon as it sees an error missing file in
the proto file. - except for EACCES on minix native for the mfs
test. also fix some fmt warnings.
. init: include debug info in executable