Buffet: Move buffet over to platform2 from src/platform/buffet. This change also open-sources buffet. The only change in this CL is the removal of the Makefile and addition of the buffet.gyp file. BUG=chromium:355180 TEST=USE=buffet emerge-gizmo platform2 Change-Id: Ibf8d3ac3f38313f82a9c07d79932b6f30130f9c5