Merge branch 'ticket28879' into maint-0.3.5

  o Minor bugfixes (correctness):

    - Fix an unreached code-path where we checked the value of "hostname"

      inside send_resolved_hostnam_cell(). Previously, we used it before

      checking it; now we check it first. Fixes bug 28879; bugfix on

      0.1.2.7-alpha.

  char buf[RELAY_PAYLOAD_SIZE];

  size_t buflen;

  uint32_t ttl;

  if (BUG(!hostname))

    return;

  size_t namelen = strlen(hostname);

  tor_assert(hostname);

  tor_assert(namelen < 256);

  ttl = dns_clip_ttl(conn->address_ttl);