dnsmasq: bump to version 2.61 and enhance

Bump to dnsmasq version 2.61.
Add new conntrack functionality: makes for more sturdy firewall setups.
Make IDN build without libintl, it's no longer needed and problematic
for other packages when there's no NLS support enabled.
Locale support does require IDN so just build it when IDN=y.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>