Reduce hash allocations in route_set

When generating a url with `url_for` the hash of arguments passed in, is dup-d and merged a TON. I wish I could clean this up better, and might be able to do it in the future. This change removes one dup, since it's literally right after we just dup-d the hash to pass into this constructor.

This may be a breaking, change but the tests pass...so :shipit: we can revert if it causes problems

This change buys us 205,933 bytes of memory and 887 fewer objects per request.

actionpack/lib/action_dispatch/routing/route_set.rb

@@ -598,7 +598,7 @@ class Generator
 
         def initialize(named_route, options, recall, set)
           @named_route = named_route
-          @options     = options.dup
+          @options     = options
           @recall      = recall.dup
           @set         = set