peerdb/tripe-newpeers.in: Don't start duplicate resolver queries.

peerdb/tripe-newpeers.in: Don't start duplicate resolver queries.

Resolver queries are indexed by query domain name.  Previously, if we
find another place which wants the same name resolved, we'd overwrite
the existing query with the new one, which causes the old one to be
cancelled (despite it possibly having made progress).

(This also avoids tickling a bug in mLib's handling of aborted queries,
fixed separately.)