lighttpd: fix build failure without ipv6

Reported in https://bugs.gentoo.org/show_bug.cgi?id=486426
and http://redmine.lighttpd.net/issues/2515
Autobuilders didn't hit it yet, but i did.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
Reviewed-by: Markos Chandras <markos.chandras@imgtec.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/lighttpd/lighttpd-02-mod_extforward.patch

@@ -0,0 +1,14 @@
+From http://redmine.lighttpd.net/issues/2515
+
+Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
+
+--- a/src/mod_extforward.c	(revision 2909)
++++ b/src/mod_extforward.c	(working copy)
+@@ -439,7 +439,6 @@
+ #ifdef HAVE_IPV6
+ 		ipstr_to_sockaddr(srv, real_remote_addr, &sock);
+ #else
+-		UNUSED(addrs_left);
+ 		sock.ipv4.sin_addr.s_addr = inet_addr(real_remote_addr);
+ 		sock.plain.sa_family = (sock.ipv4.sin_addr.s_addr == 0xFFFFFFFF) ? AF_UNSPEC : AF_INET;
+ #endif