Submitted upstream at https://github.com/lavv17/lftp/pull/307

diff -u -r ../lftp-4.7.5/src/Resolver.cc ./src/Resolver.cc
--- ../lftp-4.7.5/src/Resolver.cc	2016-11-25 11:43:16.000000000 -0500
+++ ./src/Resolver.cc	2017-01-06 05:52:18.318574544 -0500
@@ -318,7 +318,7 @@
    case AF_INET6:
       if(sizeof(add.in6.sin6_addr) != len)
          return;
-      if(IN6_IS_ADDR_LINKLOCAL(address) && scope==0) {
+      if(IN6_IS_ADDR_LINKLOCAL((const struct in6_addr*)address) && scope==0) {
 	 error=_("Link-local IPv6 address should have a scope");
 	 return;
       }