This one is a simple one.  We failed to skip the A record for the host
with -6.  It would also fail with -4.  Thanks.  Now for review.

diff --git a/bin/nsupdate/nsupdate.c b/bin/nsupdate/nsupdate.c
index c922cf9765..a13a38ad04 100644
--- a/bin/nsupdate/nsupdate.c
+++ b/bin/nsupdate/nsupdate.c
@@ -944,11 +944,15 @@ setup_system(void) {
                        case AF_INET:
                                if (have_ipv4) {
                                        sa->type.sin.sin_port = htons(dnsport);
+                               } else {
+                                       continue;
                                }
                                break;
                        case AF_INET6:
                                if (have_ipv6) {
                                        sa->type.sin6.sin6_port = htons(dnsport);
+                               } else {
+                                       continue;
                                }
                                break;
                        default: