Log Message:
Update mysql-proxy to 0.8.4. Mark as for lua51 only.

- The admin plugin now rejects empty passwords.
- Building with automake 1.13 is now supported. (Bug #17776451)
- A too-strict test for protocol state resulted in writing excessive
  log output. (Bug #17434833)
- Chassis log rotation functions did not work on Windows. (Bug #17275852)
- Calls to network_address_set_address() returned a malformed value
  on Windows. (Bug #16664004)
- MySQL Proxy libtool-archive .la files were inadvertently included with
  distributions. (Bug #14773448)
- MySQL Proxy crashed when started with an unknown option. (Bug #14665885)
- MySQL Proxy could fail to connect to the IPv6 loopback address.
  (Bug #14677085)
- If MySQL Proxy was configured to listen on a Unix socket file, it failed
  to remove the file when exiting, causing the next Proxy instance to fail
  at startup. (Bug #60781, Bug #14198411)
- The connected_clients value was incremented even if the backend was down.
  (Bug #66399, Bug #16389293)
- A memory leak resulted from a missing callback to the memory-free function.
- MySQL Proxy blocked port 4040.
- Incorrect README files were included in distributions.