resolved: properly handle BADCOOKIE DNS error

Add this new error code (documented in RFC7873) to our list of known errors.

src/resolve/resolved-dns-packet.c

@@ -2289,6 +2289,7 @@ static const char* const dns_rcode_table[_DNS_RCODE_MAX_DEFINED] = {
         [DNS_RCODE_BADNAME] = "BADNAME",
         [DNS_RCODE_BADALG] = "BADALG",
         [DNS_RCODE_BADTRUNC] = "BADTRUNC",
+        [DNS_RCODE_BADCOOKIE] = "BADCOOKIE",
 };
 DEFINE_STRING_TABLE_LOOKUP(dns_rcode, int);
 

src/resolve/resolved-dns-packet.h

@@ -263,6 +263,7 @@ enum {
         DNS_RCODE_BADNAME = 20,
         DNS_RCODE_BADALG = 21,
         DNS_RCODE_BADTRUNC = 22,
+        DNS_RCODE_BADCOOKIE = 23,
         _DNS_RCODE_MAX_DEFINED,
         _DNS_RCODE_MAX = 4095 /* 4 bit rcode in the header plus 8 bit rcode in OPT, makes 12 bit */
 };