INIT died problem / build system robustness

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

Change-Id: I8eea4986a4f64ecaf223aff5da321d8b4f4a3fa4