Syslog is socket activated since at least systemd v35 so we can drop
this dependency. Debian's linitian otherwise complains about it.

References:

    http://www.freedesktop.org/wiki/Software/systemd/syslog/
    http://lintian.debian.org/tags/systemd-service-file-refers-to-obsolete-target.html

This enhancement virtlockd so that it can receive a pre-opened
UNIX domain socket from systemd at launch time, and adds the
systemd service/socket unit files

* daemon/libvirtd.service.in: Require virtlockd to be running
* libvirt.spec.in: Add virtlockd systemd files
* src/Makefile.am: Install systemd files
* src/locking/lock_daemon.c: Support socket activation
* src/locking/virtlockd.service.in, src/locking/virtlockd.socket.in:
  systemd unit files
* src/rpc/virnetserverservice.c, src/rpc/virnetserverservice.h:
  Add virNetServerServiceNewFD() method
* src/rpc/virnetsocket.c, src/rpc/virnetsocket.h: Add virNetSocketNewListenFD
  method
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>