deps: c-ares float, win ipv6 bad fec0 prefix

Was 72c5458:

  PR-URL: #5090
  Reviewed-By: Fedor Indutny <fedor@indutny.com>

Reimplemented for c-ares 1.13.0

PR-URL: #15378
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

PR-URL: #19939
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

Author: rvagg

deps/cares/src/ares_init.c

@@ -1272,6 +1272,11 @@ static int get_DNS_AdaptersAddresses(char **outptr)
       }
       else if (namesrvr.sa->sa_family == AF_INET6)
       {
+        /* Windows apparently always reports some IPv6 DNS servers that
+         * prefixed with fec0:0:0:ffff. These ususally do not point to
+         * working DNS servers, so we ignore them. */
+        if (strncmp(addresses[addressesIndex].text, "fec0:0:0:ffff:", 14) == 0)
+          continue;
         if (memcmp(&namesrvr.sa6->sin6_addr, &ares_in6addr_any,
                    sizeof(namesrvr.sa6->sin6_addr)) == 0)
           continue;