Don't send uninitialized stack to the controller and say it's a date.

Fixes bug 11519, apparently bugfix on 0.2.3.11-alpha.

changes/bug11519

@@ -0,0 +1,3 @@
+  o Minor bugfixes:
+    - Avoid sending an garbage value to the controller when a circuit is
+      cannibalized. Fixes bug 11519; bugfix on 0.2.3.11-alpha.

src/or/circuituse.c

@@ -1310,7 +1310,7 @@ circuit_launch_by_extend_info(uint8_t purpose,
     circ = circuit_find_to_cannibalize(purpose, extend_info, flags);
     if (circ) {
       uint8_t old_purpose = circ->_base.purpose;
-      struct timeval old_timestamp_created;
+      struct timeval old_timestamp_created = circ->_base.timestamp_created;
 
       log_info(LD_CIRC,"Cannibalizing circ '%s' for purpose %d (%s)",
                build_state_get_exit_nickname(circ->build_state), purpose,