ipv6-allow-binding-to-ipv6-address-in-iface
ipv6-allow-binding-to-ipv6-address-in-iface

ipv4 and ipv6 binding to a named interface works OK.  ipv4 binding to an IP also
works, but we need some extra ipv6 magic to identify the ipv6 interface from an
ipv6 address.

This patch based on code from "user3546716" at
http://stackoverflow.com/questions/13504934/binding-sockets-to-ipv6-addresses

adds the necessary magic.

https://github.com/warmcat/libwebsockets/issues/717
sartura/libwebsockets,sartura/libwebsockets,sartura/libwebsockets,sartura/libwebsockets,sartura/libwebsockets,sartura/libwebsockets,sartura/libwebsockets