systemd: Backport newer bbclass to fix QA warnings

:Release Notes:
systemd.bbclass in newer oe-core removes /lib/systemd automatically
when systemd isn't included in DISTRO_FEATURES.

:Detailed Notes:
Fixes following QA warnings:
ntp-4.2.6p5: ntp: Files/directories were installed but not shipped
  /lib/systemd/system/sntp.service
  /lib/systemd/system/ntpd.service
ypbind-mt-1.36: ypbind-mt: Files/directories were installed but not
  shipped
  /lib
  /lib/systemd
  /lib/systemd/system
  /lib/systemd/system/ypbind.service
dnsmasq-2.55: dnsmasq: Files/directories were installed but not shipped
  /lib
  /lib/systemd
  /lib/systemd/system
  /lib/systemd/system/dnsmasq.service
yp-tools-2.12: yp-tools: Files/directories were installed but not
  shipped
  /lib
  /lib/systemd
  /lib/systemd/system
  /lib/systemd/system/domainname.service
zram-0.1: zram: Files/directories were installed but not shipped
  /lib
  /lib/systemd
  /lib/systemd/system
  /lib/systemd/system/zram.service

:Testing Performed:
Only build tested.

:QA Notes:
No change to image.

:Issues Addressed:
[GF-42606] Ongoing metadata improvement/cleanup work
[GF-52560] Fix or hide all known QA issues to get clear qa.log from
           verification builds

Open-webOS-DCO-1.0-Signed-off-by: Martin Jansa <martin.jansa@lge.com>

Change-Id: I0ccdf19ba94ba8da50f48731ced750b4df30771d
Reviewed-on: https://g2g.palm.com/4016
Reviewed-by: DCO Verification
Reviewed-by: Martin Jansa <Martin.Jansa@lge.com>
Reviewed-by: Build Verification
Tested-by: Martin Jansa <Martin.Jansa@lge.com>
Reviewed-by: Susan Montooth <susan.montooth@lge.com>