Build ring before publishing pool strategy

marina_pool:sync/3 inserted {token_aware, N} into the foil table
before marina_ring:build/1 had compiled marina_ring_utils. A query
carrying a routing key in that window resolved the token_aware
strategy and called marina_ring_utils:lookup/1 on a module that did
not exist yet, crashing the caller with undef instead of getting
{error, marina_pool_not_started}.

Compile the ring first, so the strategy only becomes visible to
callers once the lookup module is loaded. This also applies to
topology re-syncs, where the same window reopened on every rebuild.

Author: lpgauth

src/marina_pool.erl

@@ -82,11 +82,11 @@ sync(Strategy, NewNodes, OldNodes) ->
     NewAddrs = [Addr || {Addr, _} <- NewNodes],
     lists:foreach(fun stop_node/1, OldAddrs -- NewAddrs),
     lists:foreach(fun start_node/1, NewAddrs -- OldAddrs),
-    rebuild_index(Strategy, NewNodes, length(OldNodes)),
     case Strategy of
         token_aware -> marina_ring:build(NewNodes);
         random -> ok
-    end.
+    end,
+    rebuild_index(Strategy, NewNodes, length(OldNodes)).
 
 %% private
 node({random, NodeCount}, undefined) ->