Fix two more coverity-spotted leaks in master.

One is a probably-impossible leak if we fail to sign a consensus;
another occurs when we can't look up the user we're trying to chown
our sockets to.

src/or/connection.c

@@ -1068,6 +1068,7 @@ connection_listener_new(const struct sockaddr *listensockaddr,
         log_warn(LD_NET,"Unable to chown() %s socket: user %s not found.",
                  address, options->User);
         tor_close_socket(s);
+        goto err;
       } else if (chown(address, pw->pw_uid, pw->pw_gid) < 0) {
         log_warn(LD_NET,"Unable to chown() %s socket: %s.",
                  address, strerror(errno));

src/or/dirvote.c

@@ -2121,7 +2121,7 @@ networkstatus_compute_consensus(smartlist_t *votes,
                                        digest, digest_len,
                                        signing_key)) {
       log_warn(LD_BUG, "Couldn't sign consensus networkstatus.");
-      return NULL; /* This leaks, but it should never happen. */
+      goto done;
     }
     smartlist_add(chunks, tor_strdup(sigbuf));