common-mk: Move Buffet out of platform2 ebuild.

Create a separate ebuild for Buffet.

BUG=chromium:407655
TEST=USE=buffet FEATURES emerge-link platform2
     USE=buffet FEATURES emerge-link buffet
CQ-DEPEND=CL:214221

Change-Id: Ibd5304a5184e7a768b0afcb17269a55f0928b280
Reviewed-on: https://chromium-review.googlesource.com/214244
Tested-by: Alex Vakulenko <avakulenko@chromium.org>
Reviewed-by: Bertrand Simonnet <bsimonnet@chromium.org>
Commit-Queue: Alex Vakulenko <avakulenko@chromium.org>
1 file changed