unbound: improve a few UCI settings

- treat RFC6762 'local.' as nxdomain because avahi and other services
will disable if SOA or NS records appear in central DNS.
- allow two threads to be enabled with the 'heavy traffic' variant of
Unbound packages.

Signed-off-by: Eric Luehrsen <ericluehrsen@gmail.com>

net/unbound/files/unbound.uci

@@ -14,6 +14,7 @@ config unbound
 	option listen_port '53'
 	option localservice '1'
 	option manual_conf '0'
+	option num_threads '1'
 	option protocol 'default'
 	option query_minimize '0'
 	option query_min_strict '0'