gnomeos: Add basic device files in /dev

So we're more usable in a chroot for compiling software.

gnomeos/yocto/classes/gnomeos-contents.bbclass

@@ -67,6 +67,16 @@ EOF
 	    mkdir $d
 	done
 	chmod a=rwxt tmp
+
+	# Populate /dev/ with a bare minimum of devices, so that
+	# the tree is usable for building software inside a chroot
+	# without devtmpfs mounted
+	mknod -m 0666 ./dev/null c 1 3
+	mknod -m 0666 ./dev/zero c 1 5
+	mknod -m 0666 ./dev/full c 1 7
+	mknod -m 0666 ./dev/random c 1 8
+	mknod -m 0666 ./dev/urandom c 1 9
+
 	for d in $READONLY_BIND_MOUNTS; do
             mv ${IMAGE_ROOTFS}/$d .
 	done