Debian initscript tweak.

Dnsmasq's startup script seems to assume users always want to use
dnsmasq as local DNS resolver, and tells resolvconf to put
"nameserver 127.0.0.1" in /etc/resolv.conf
The problem with this is that if users just want to use dnsmasq
as DHCP server, and put port=0 in /etc/dnsmasq.conf to disable
the DNS functionality, they end up with broken name resolving.

Put a basic check in the startup script that skips resolvconf
configuration if a line starting with port=0 is in /etc/dnsmasq.conf
This doesn't cover all cases (e.g. configuration could also be in
different file in /etc/dnsmasq.d), but is better than current
situation.

debian/init

@@ -154,6 +154,11 @@ start_resolvconf()
 		[ $interface = lo ] && return
 	done
 
+# Also skip this if DNS functionality is disabled in /etc/dnsmasq.conf
+	if grep -qs '^port=0' /etc/dnsmasq.conf; then
+		return
+	fi
+
         if [ -x /sbin/resolvconf ] ; then
 		echo "nameserver 127.0.0.1" | /sbin/resolvconf -a lo.$NAME
 	fi