curl_multi_socket() fix thanks to Jeff's test code

                                  Changelog

Daniel (11 September 2006)

- Jeff Pohlmeyer presented a *multi_socket()-using program that exposed a

  problem with it (SIGSEGV-style). It clearly showed that the existing

  socket-state and state-difference function wasn't good enough so I rewrote

  it and could then re-run Jeff's program without any crash. The previous

  version clearly could miss to tell the application when a handle changed

  from using one socket to using another.

  While I was at it (as I could use this as a means to track this problem

  down), I've now added a 'magic' number to the easy handle struct that is

  inited at curl_easy_init() time and cleared at curl_easy_cleanup() time that

  we can use internally to detect that an easy handle seems to be fine, or at

  least not closed or freed (freeing in debug builds fill the area with 0x13

  bytes but in normal builds we can of course not assume any particular data

  in the freed areas).

Daniel (9 September 2006)

- Michele Bini fixed how the hostname is put in NTLM packages. As servers

  don't expect fully qualified names we need to cut them off at the first dot.

This release includes the following bugfixes:

 o fixed a socket state problem with *multi_socket()

 o (HTTP) NTLM hostname fix

 o getsockname usage fixes

 o SOCKS5 proxy connects can now time-out

 Domenico Andreoli, Armel Asselin, Gisle Vanem, Yang Tse, Andrew Biggs,

 Peter Sylvester, David McCreedy, Dmitriy Sergeyev, Dmitry Rechkin,

 Jari Sundell, Ravi Pratap, Michele Bini

 Jari Sundell, Ravi Pratap, Michele Bini, Jeff Pohlmeyer

        Thanks! (and sorry if I forgot to mention someone)