- Made the SOCKS code use the new Curl_read_plain() function to fix the bug

  Markus Moeller reported: http://curl.haxx.se/mail/archive-2008-09/0016.html

- recv() errors other than those equal to EAGAIN now cause proper
  CURLE_RECV_ERROR to get returned. This made test case 160 fail so I've now
  disabled it until we can figure out another way to exercise that logic.