chg: [host] only install ``ntp`` if not using ``systemd-timesyncd``

precise/host/hooks/install.d/38-ntp.sh

@@ -1,4 +1,7 @@
 #!/bin/bash
 
-apt-get install ntp -y </dev/null
+
+if ! [ -e /lib/systemd/systemd-timesyncd ]; then
+    apt-get install ntp -y </dev/null
+fi