units: add 'SmackFileSystemRoot=*' option into tmp.mount

If SMACK is enabled, 'smackfsroot=*' option should be specified when
/tmp is mounted since many non-root processes use /tmp for temporary
usage. If not, /tmp is labeled as '_' and smack denial occurs when
writing.

In order to do that, 'SmackFileSystemRoot=*' is newly added into
tmp.mount.

units/tmp.mount

@@ -1,21 +0,0 @@
-#  This file is part of systemd.
-#
-#  systemd is free software; you can redistribute it and/or modify it
-#  under the terms of the GNU Lesser General Public License as published by
-#  the Free Software Foundation; either version 2.1 of the License, or
-#  (at your option) any later version.
-
-[Unit]
-Description=Temporary Directory
-Documentation=man:hier(7)
-Documentation=http://www.freedesktop.org/wiki/Software/systemd/APIFileSystems
-ConditionPathIsSymbolicLink=!/tmp
-DefaultDependencies=no
-Conflicts=umount.target
-Before=local-fs.target umount.target
-
-[Mount]
-What=tmpfs
-Where=/tmp
-Type=tmpfs
-Options=mode=1777,strictatime