dnsmasq: tweaks for .olsr domains

[pktpls]

Maintainer:
Environment:

Description:
I propose two little tweaks to how we handle .olsr domains, similar to freifunk-berlin/bbb-configs#406:

1. Never forward .olsr queries to public resolvers

   Queries for *.olsr should never be forwarded to public resolvers.
   Some resolvers drop queries for unknown TLDs, without a response.

   As a result, our query waits for a long time and eventually times out.
   This affects A queries for unknown hosts, and also all AAAA queries.

   Happy Eyeballs means an AAAA query is sent almost always,
   even though *.olsr is really only used for our IPv4 networking,
   and so we get lots of very slow DNS queries...

   This can be avoided very simply by not forwarding .olsr queries:

   server=/olsr/

2. Define our own .olsr domains independently of OLSRd

   Dnsmasq only picks up our own .olsr domain names
   once OLSR had first flushed its nameservice hosts file, and once
   dnsmasq actually reloaded its config. This could take up to 5 minutes.
   Until then, our own .olsr domains were not resolvable.

   Instead we could explicitly tell dnsmasq about our own .olsr domain names.
   As a result, they can be resolved instantly once dnsmasq is running.

   Neat side effect: proper .olsr hostnames in Reverse DNS and traceroute.
   Before this patch, the first hop would only report as 'frei.funk'.

I briefly tried to implement these two myself, but got lost in the forest of different packages :)