MSVC fixes

Fixes to allow compilation with Microsoft Visual Studio 2008

* Fixed several instances of declarations after statements.

* In socket.c, fixed issue where uninitialized value (err)
  is being passed to to gai_strerror.

* ssl.c is trying to access multi_output_peer_info_env
  function in multi.c, causing an undefined symbol warning
  at compile time.  ssl.c is strictly a client of multi.c
  (but not the other way around), therefore ssl.c does not
  include multi.h and should not depend on multi.h API.  To
  fix, moved validate_peer_info_line and multi_output_peer_info_env
  from multi.c to misc.c.

* MSVC doesn't support %z as a printf format specifier for size_t

* MSVC doesn't support a const variable being used to dimension
  an array.

* Explicitly cast the third parameter to setsockopt to
  const void *