Issues:
  Makefile can't clean completely as if remove the .config file, then it generates other files
  Its a catch22 in that the hash of the config needs the config, so it generates the config, but
  also it does some stuff before that without the .config and generates an empty hash and things
  screw up from a fresh checkout state. If a .config file exists already, it is fine.
  Probably just need better dependancies