Backport upstream fixes for Gentoo bug #636650

Original upstream commit message:

Author: nicorac <claudio.nicora@gmail.com>
Date:   Wed Oct 25 16:48:24 2017 +0200

    [core] fix build --disable-ipv6 (fixes #2832)
    
    x-ref:
      "Build error on systems without IPV6 support (regression from 1.4.46)"
      https://redmine.lighttpd.net/issues/2832
    
    github: closes #87

--- a/src/network.c
+++ b/src/network.c
@@ -77,9 +77,13 @@ static void network_host_normalize_addr_str(buffer *host, sock_addr *addr) {
     if (addr->plain.sa_family == AF_INET6)
         buffer_append_string_len(host, CONST_STR_LEN("]"));
     if (addr->plain.sa_family != AF_UNIX) {
+      #ifdef HAVE_IPV6
         unsigned short port = (addr->plain.sa_family == AF_INET)
           ? ntohs(addr->ipv4.sin_port)
           : ntohs(addr->ipv6.sin6_port);
+      #else
+        unsigned short port = ntohs(addr->ipv4.sin_port);
+      #endif
         buffer_append_string_len(host, CONST_STR_LEN(":"));
         buffer_append_int(host, (int)port);
     }