make lxc-shutdown -h work

It was calling non-existent 'help'

Signed-off-by: Timothy Chen <tnachen@gmail.com>
Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com>
Signed-off-by: Daniel Lezcano <dlezcano@fr.ibm.com>

src/lxc/lxc-shutdown.in

@@ -60,7 +60,7 @@ dowait=0
 while true; do
     case "$1" in
     -h|--help)
-        help
+        usage
         exit 1
         ;;
     -n|--name)