systemd: add systemd recipes

Add systemd recipes and associated support recipes.

Mostly based on meta-oe/meta-systemd, so almost all credit should go to:

Andreas Müller <schnitzeltony@googlemail.com>
Denis 'GNUtoo' Carikli <GNUtoo@no-log.org>
Holger Hans Peter Freyther <holger@moiji-mobile.com>
Khem Raj <raj.khem@gmail.com>
Koen Kooi <koen@dominion.thruhere.net>
Martin Jansa <Martin.Jansa@gmail.com>

(From OE-Core rev: 6a8a48b4d0d0b9b8d8af46cae11245bcb870bbc3)

Signed-off-by: Radu Moisan <radu.moisan@intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-core/systemd/systemd-serialgetty/serial-getty@.service

@@ -0,0 +1,32 @@
+#  This file is part of systemd.
+#
+#  systemd is free software; you can redistribute it and/or modify it
+#  under the terms of the GNU General Public License as published by
+#  the Free Software Foundation; either version 2 of the License, or
+#  (at your option) any later version.
+
+[Unit]
+Description=Serial Getty on %I
+BindTo=dev-%i.device
+After=dev-%i.device systemd-user-sessions.service
+
+# If additional gettys are spawned during boot then we should make
+# sure that this is synchronized before getty.target, even though
+# getty.target didn't actually pull it in.
+Before=getty.target
+
+[Service]
+Environment=TERM=vt100
+ExecStart=-/sbin/agetty -s %I @BAUDRATE@
+Restart=always
+RestartSec=0
+UtmpIdentifier=%I
+TTYPath=/dev/%I
+TTYReset=yes
+TTYVHangup=yes
+KillMode=process
+IgnoreSIGPIPE=no
+
+# Some login implementations ignore SIGTERM, so we send SIGHUP
+# instead, to ensure that login terminates cleanly.
+KillSignal=SIGHUP