sfml2 network should use getaddrinfo instead of gethostbyname

[etam]

Gethostbyname is obsolete. Getaddrinfo should be used.

1. It's written in http://kernel.org/doc/man-pages/online/pages/man3/gethostbyname.3.html
2. Packaging sfml2 on openSUSE gives warning:
   libsfml2-2_0.x86_64: I: binary-or-shlib-calls-gethostbyname /usr/lib64/libsfml-network.so.2.0
   The binary calls gethostbyname(). Please port the code to use getaddrinfo().

[LaurentGomila]

Thanks for your feedback.

This update will also be a good starting point for a new implementation that is able to handle multiple network interfaces on the same machine.

Here is a piece of code that I can reuse later:

    addrinfo hints;
    std::memset(&hints, 0, sizeof(hints));
    hints.ai_family = AF_INET;

    addrinfo* result = NULL;
    if (getaddrinfo("... host name ...", NULL, &hints, &result) == 0)
    {
        while (result)
        {
            sockaddr_in* addr = reinterpret_cast<sockaddr_in*>(result->ai_addr);
            Uint32 address = addr->sin_addr.s_addr;
            result = result->ai_next;
        }
        freeaddrinfo(result);
    }