o A rule which makes the include/asm symlink should have the target
  "include/asm", not "symlinks". Likewise for ".hdepend". 
  (include/linux/modversions.h yet to follow)

  Apart from being cleaner, this additionally gives us protection
  when a command fails or the user interrupts execution:
 
  E.g. for the case of "make dep", if the user interrupts at
  some point, make will delete the target (now ".hdepend") for us,
  so that at the next run, make knows that it needs to make the
  dependencies again, while otherwise it would just use the
  half-finished file.

o We don't need the include/asm symlink for the configuration targets,
  we only need it before generating dependencies.

  (The setup of having /usr/include/{linux,asm} symlinked to your
  current kernel source is already broken in 2.5, so this change
  doesn't break anything which wasn't broken before.)

o Add .hdepend to "prepare", i.e. what needs to be done before
  we can start the recursive build. That means we can get rid of
  the gross (and not always working) hack which made "make"
  run "make dep" when .hdepend didn't exist yet.

o Mark the *config targets phony and improve some comments.