Protect som cross-script invocations by checks to see that the target

script exists.  This allows pruning of rc.d scripts without getting
too many ugly boottime error message

etc/rc.d/ipfw

@@ -37,7 +37,9 @@ ipfw_start()
 	if [ -r "${firewall_script}" ]; then
 		. "${firewall_script}"
 		echo -n 'Firewall rules loaded, starting divert daemons:'
+		if [ -f /etc/rc.d/natd ] ; then
 			/etc/rc.d/natd start
+		fi
 	elif [ "`ipfw l 65535`" = "65535 deny ip from any to any" ]; then
 		echo 'Warning: kernel has firewall functionality, but' \
 		    ' firewall rules are not enabled.'
@@ -62,7 +64,9 @@ ipfw_stop()
 	# Disable the firewall
 	#
 	${SYSCTL_W} net.inet.ip.fw.enable=0
+	if [ -f /etc/rc.d/natd ] ; then
 		/etc/rc.d/natd stop
+	fi
 }
 
 load_rc_config $name

etc/rc.d/netif

@@ -57,8 +57,10 @@ network_start()
 	# Configure the interface(s).
 	network_common ifn_start verbose
 
+	if [ -f /etc/rc.d/ipfilter ] ; then
 		# Resync ipfilter
 		/etc/rc.d/ipfilter resync
+	fi
 }
 
 network_stop()