buffet: Extracted libweave into separate directory It still has references to dbus, buffet and other ChromeOS specific stuff. BUG=brillo:1235 TEST=FEATURES=test emerge-gizmo buffet Change-Id: Ib108960ee88afcf2ecdddf37ce30bd5f168c0034 Reviewed-on: https://chromium-review.googlesource.com/283509 Tested-by: Vitaly Buka <vitalybuka@chromium.org> Reviewed-by: Alex Vakulenko <avakulenko@chromium.org> Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>