Kernel: Move kernel symbols to /res/kernel.map and make it root-only

Let's lock down access to the kernel symbol table, since it trivializes
learning where the kernel functions are.

Of course, you can just build the same revision yourself locally and
learn the information, but we're taking one step at a time here. :^)

Kernel/build-root-filesystem.sh

@@ -63,7 +63,8 @@ echo "done"
 printf "installing base system... "
 cp -R ../Base/* mnt/
 cp -R ../Root/* mnt/
-cp kernel.map mnt/
+cp kernel.map mnt/res/
+chmod 400 mnt/res/kernel.map
 echo "done"
 
 printf "installing users... "