add config.{sub,guess} copies for automatic updates

The current portage code only looks in /usr/share/gnuconfig/ for these
files.  Add our own local copies and update from there until we figure
out a better solution.

TEST=emerge glob now passes (and config.sub doesn't abort)

Change-Id: I6355504d4a50d7e647a21ade5eb26cff604fd68c
3 files changed
tree: 588e41438b909244c924819ed8976007e203364b
  1. etc/
  2. usr/
  3. .gitignore
  4. setup_board