sysnetwork: put systemd_read_resolved_runtime in an ifdef

commit f865919872
(Interface to read /run/systemd/resolve/resolv.conf)
Added an interface to sysnet_read_config which requires the systemd
module loaded. Putting the interface in an optional_policy() is not
possible since sysnet_read_config is called from several tunables so
we use an ifdef.

policy/modules/system/sysnetwork.if

@@ -348,7 +348,9 @@ interface(`sysnet_read_config',`
 	files_search_etc($1)
 	allow $1 net_conf_t:file read_file_perms;
 
-	systemd_read_resolved_runtime($1)
+	ifdef(`init_systemd',`
+		systemd_read_resolved_runtime($1)
+	')
 
 	ifdef(`distro_debian',`
 		files_search_pids($1)