New image framework generation

The CD now boots directly from the ISO 9660 filesystem instead of using
MBR partitioning with Minix file systems. This saves some space on the
CD and reduces memory requirements by some unknown amount as the root
ramdisk is completely eliminated.

The x86 hard drive image creation is also rewritten in the same
fashion.

The setup is modified to be more NetBSD-like (unpacking sets
tarballs instead of blindly copying the CD contents). Splitting MINIX
into sets is done in another commit due to it being a nightmare to
rebase.

Since MINIX lacks union mounts for now, a bunch of ramdisks are
generated at run-time to make parts of the filesystem writeable for the
CD. This solution isn't ideal, but it's enough for an installation CD.

Change-Id: Icbd9cca4dafebf7b42c345b107a17679a622d5cd

etc/usr/daily

@@ -3,7 +3,7 @@
 # daily - daily cleanup of the system.
 
 # Doesn't make sense when running from CD
-if [ -f /CD ]
+if [ ! -z $(sysenv bootcd) ]
 then	exit
 fi
 
@@ -50,8 +50,8 @@ cycle()
     fi
 }
 
-cycle 100 wtmp 
-cycle 100 log 
+cycle 100 wtmp
+cycle 100 log
 cycle  20 ftplog
 cycle 200 aftplog
 

etc/usr/rc

@@ -178,6 +178,11 @@ start|autoboot)
     	cat < $RANDOM_FILE >/dev/random
     	# overwrite $RANDOM_FILE. We don't want to use this data again
     	dd if=/dev/random of=$RANDOM_FILE bs=1024 count=1 2> /dev/null
+    else
+	# We couldn't find the old state to restart from, so use a binary
+	# file and the current date instead, even if this is less than ideal.
+	cat /bin/sh >> /dev/urandom
+	date >> /dev/urandom
     fi
 
     # start network driver instances for all configured ethernet devices