Oops; _actually_ enable microdesc-by-default for clients

It turns out that it wasn't enough to set the configuration to
"auto", since the correct behavior for "auto" had been disabled in
microdesc.c.   :p

(Hasn't been in a release yet, so doesn't need a changes entry.)

src/or/microdesc.c

@@ -698,14 +698,8 @@ we_use_microdescriptors_for_circuits(const or_options_t *options)
   int ret = options->UseMicrodescriptors;
   if (ret == -1) {
     /* UseMicrodescriptors is "auto"; we need to decide: */
-#if 0
     /* So we decide that we'll use microdescriptors iff we are not a server */
     ret = ! server_mode(options);
-#else
-    /* We don't use microdescs for now: not enough caches are running
-     * 0.2.3.1-alpha */
-    ret = 0;
-#endif
   }
   return ret;
 }