Increase number of preemptive internal circuits

When we connect to a hidden service as a client we may need three internal
circuits, one for the descriptor retrieval, introduction, and rendezvous.
Let's try to make sure we have them. Closes #13239.

Signed-off-by: David Goulet <dgoulet@ev0ke.net>

changes/bug13239

@@ -0,0 +1,4 @@
+  o Minor bugfixes (hidden service client):
+    - Increase the minimum number of internal circuits we preemptively build
+      from 2 to 3 so they are available when a client connects to another
+      onion service. Fixes bug 13239; bugfix on tor-0.1.0.1-rc~460.

src/or/circuituse.c

@@ -1067,7 +1067,7 @@ circuit_predict_and_launch_new(void)
   if (rep_hist_get_predicted_internal(now, &hidserv_needs_uptime,
                                       &hidserv_needs_capacity) &&
       ((num_uptime_internal<2 && hidserv_needs_uptime) ||
-        num_internal<2)
+        num_internal<3)
         && router_have_consensus_path() != CONSENSUS_PATH_UNKNOWN) {
     if (hidserv_needs_uptime)
       flags |= CIRCLAUNCH_NEED_UPTIME;