systemd/selinux init scripts fixups

- RHEL/OL 7 doesn't have the ifconfig command by default so have the
  lxc-net script check for its existence before use, and fall back
  to using the ip command if ifconfig is not available

- When lxc-net is run from systemd on a system with selinux enabled,
  the mkdir -p ${varrun} will create /run/lxc as init_var_run_t which
  dnsmasq can't write its pid into, so we restorecon it
  after creation (to var_run_t)

- The lxc-net systemd .service file needs an [Install] section so that
  "systemctl enable lxc-net" will work

Signed-off-by: Dwight Engen <dwight.engen@oracle.com>
lxc-test-unpriv: test for different cgroups per subsystem

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
lxc-test-apparmor-mount: don't clear out /etc/lxc/lxc-usernet

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
fix lxc.mount.auto clearing

the way config_mount was structured, sending 'lxc.mount.auto = '
ended up actually clearing all lxc.mount.entrys.  Fix that by
moving the check for an empty value to after the subkey checks.
Then, actually do the clearing of auto_mounts in config_mount_auto.

The 'strlen(subkey)' check being removed was bogus - the subkey
either known to be 'lxc.mount.entry', else subkey would have been
NULL (and forced a return in the block above).

This would have been clearer if the config_mount() and helper
fns were structured like the rest of confile.c.  It's tempting
to switch it over, but there are subtleties in there so it's
not something to do without a lot of thought and testing.

Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
conf.c: Define MS_PRIVATE for Android

Signed-off-by: Stéphane Graber <stgraber@ubuntu.com>