systemd unit: Make sure network is really up

Change network.target to network-online.target to make sure network is
really up and running when starting corosync.

Signed-off-by: Jan Friesse <jfriesse@redhat.com>
Reviewed-by: Christine Caulfield <ccaulfie@redhat.com>

init/corosync.service.in

@@ -1,8 +1,8 @@
 [Unit]
 Description=Corosync Cluster Engine
 ConditionKernelCommandLine=!nocluster
-Requires=network.target
-After=network.target
+Requires=network-online.target
+After=network-online.target
 
 [Service]
 ExecStart=@INITWRAPPERSDIR@/corosync start