update dependencies for clock service

The clock services had a very long list of "before" dependencies that
referred to other services within OpenRC. For ease of maintenance,
convert these to "after clock" dependencies in the individual services.

init.d/urandom.in

@@ -14,6 +14,7 @@ description="Initializes the random number generator."
 
 depend()
 {
+	after clock
 	need localmount
 	keyword -docker -jail -lxc -openvz -prefix -systemd-nspawn
 }