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

sbin/init/Makefile

@@ -7,6 +7,12 @@ DPADD=	${LIBUTIL}
 LDADD=	-lutil
 CPPFLAGS+=	-DMFS_DEV_IF_NO_CONSOLE -DSUPPORT_UTMP -DSUPPORT_UTMPX
 
+#.if defined(__MINIX)
+# BJG - by default produce line numbers in case init exits without producing
+# output
+DBG=-g
+#.endif
+
 .ifdef	 INIT_CHROOT
 CPPFLAGS+=	-DCHROOT
 .elifdef SMALLPROG