edgeos: add synce4l package

This is an open source package we are currently installing via
google3/third_party. It is not available from Gentoo upstream, so I
manually uploaded it to the mirror and wrote a simple ebuild.

Installs to /usr/sbin because the Makefile's default /usr/local/sbin is
a stateful_overlay in our image, so any packages we installed there
would get messed up when we mount the overlayfs.

Note that the google3 code will overwrite this version with the one we
compiled from google3/third_party imports. I will send a followup
google3 CL to reveal this package in the image.

BUG=b/282240260
TEST=built a baseimage and verified the package installed to /usr/sbin
TEST=built a google3 release image and verified this version was overwritten for now
RELEASE_NOTE=add synce4l package

Change-Id: I2ffd96aa240161e3b4706daa0cd3c46a438643a9
Reviewed-on: https://cos-review.googlesource.com/c/cos/overlays/board-overlays/+/49810
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Joshua Emele <jemele@google.com>
6 files changed