systemd: Backports fixes to 216

systemd: Backports fixes to 216

Fix systemd-timesyncd assertion

when networkd is disabled then we now do not
create /run/systemd/netif/links but timesyncd needs it. So lets
manually create this file when networkd is disabled so timesyncd
can still function

When enabling systemd-timesyncd we need systemd-timesync user

Backport patches to enable timesyncd when resolved and networkd
are disabled

replace the resolv.conf symlinink patch with a proper backport

Change-Id: I53f1a53eec4e4a4dbdfb7e8cd155d544ee5d81ec
Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>