Added API to create a set of UDP dispatches which can be shared
round-robin style when making upstream queries for authoritative
data; this should reduce lock contention in the query source
dispatch.
to 10. Allow setting this in named.conf using the new
'resolver-query-timeout' option, which specifies a max
time in seconds. 0 means 'default' and anything longer
than 30 will be silently set to 30. [RT #22852]