Fix a memory leak

It happened in dirvote_add_signatures_to_pending_consesus().

changes/bug1831

   o Minor bugfixes
     - Fix a memory leak in the error case of circuit_build_times_parse_state().
       Bugfix on 0.2.2.14-alpha; fixes bug 1831 partially.
+    - Fix a memory leak in dirvote_add_signatures_to_pending_consensus(). 
+      Bugfix on 0.2.2.6-alpha; fixes bug 1831 partially.

src/or/dirvote.c

@@ -3008,6 +3008,7 @@ dirvote_add_signatures_to_pending_consensus(
       networkstatus_vote_free(v);
     }
     *msg_out = "Signatures added";
+    tor_free(new_signatures);
   } else if (r == 0) {
     *msg_out = "Signatures ignored";
   } else {