systemd: Enable DHCPv6 and Ipv6AcceptRA.

This will enable a COS node to get an ipv6 address via DHCP, and apply
routes advertised by the DHCP server.

In addition, it is also adding a patch where the boot process of  VM
with the above configuration enabled should not regress if there is only
IPV4 address available.

TEST=presubmit and validation test; testing mentioned in
RELEASE_NOTE=Enabled COS VM to get an IPV6 address if available.

Change-Id: I2289d7e48ed6f4179e3104d5bdff32ad7c966252
Reviewed-by: Robert Kolchmeyer <>
Tested-by: Cusky Presubmit Bot <>
4 files changed