posix_shutdown, posix_socket, socklen_t) [_WIN32]: Move socket
related externs to sys/socket.h.
(inet_ntop) [_WIN32]: Move extern to inet.h.
(tcp_listen): Remove the !WIN32 includes and use the revised
sys/socket.h, netinet/in.h, arpa/inet.h and netdb.h.
Move CANT_REACH() and return -1 into a default case.
Removes warnings for MinGW of potential missing cases.
(posix_accept, posix_socket) [_WIN32]: Switch handle to SOCKET
to match Windows call. Cast to an int for translation map.
Remove the extern posix_fileno().
(fileno) [_WIN32]: Replace system fileno() with a function that supports posix
file descriptors. Move #undef fileno to w32misc.h as the system define
is in stdio.h.
(rea) [_WIN32]: Add stdio.h for fileno() extern declaration and add misc.h
to ensure the WIN32 fixes to stdio.h are included.
[_WIN32]: New in.h, inet.h, netdb.h. Windows equivalent for POSIX
includes.
(tcp_connect): Use new include files and inet_ntop().
Allows tcp_connect() to compile when HAVE_GETADDRINFO is enabled.
SO_REUSEADDR code for _WIN32 from tcp_listen() to
posix_setsockopt().
[_WIN32] (posix_open): Switch to _sopen() for _sopen_s() as MinGW
does not support _sopen_s() yet.
[_WIN32] (posix_fd2socket): Fix typo.
